I'm not familiar with the bookstores in your area, but I like bookshop approaches for several reasons:
you should be a reader yourself in order to approach women at bookshops, but I'm a novelist and poet myself (which women often find fascinating), so bookshops are attractive 'hunting grounds' for me.
For non-readers, you can approach women to ask them about books you might want to gift to a friend or something like that, but you'd show yourself to women who read and might not be interested in a non-reader.
I want to like bookstore approaches but I have found them problematic. I say this as a man who likes reading and exploring concepts. Over the years, it has been a disappointment to me that bookstores have not been a more fruitful venue for arranging dates. There also aren't many viable approaches in my experience.
There are two main bookstore chains in my area. There's Barnes & Noble, which is still the behemoth of bookstores in the United States. There's also one smaller chain that is a book discounter. I would rather buy books at this location because the prices are better than Barnes & Noble. The audience at this bookstore is less good looking because it is less upscale. Barnes & Noble is overall the better option for approaching as it has more physically attractive people.
bookshop customers are in general 'browsing' and not in a a hurry
with regards to 'prospects', Dutch bookshops seem to have plenty of customers any time of the day, and the majority is female
I'd agree on the unhurried part in my area as well. There are customers at the bookstores I've mentioned, but a lot are either married, older women and/or unattractive women. When I have tried to do bookstore approaches, I've generally tried on weekends.
approaches are not 'cold' as you can see what books readers are looking for, which tells you a lot about a woman
opening conversations are easy, you can ask customers about likes and dislikes, or advice...readers often like to discuss what they read
I disagree on the 'coldness' of an approach. A bookstore approach is still approaching a stranger. Stranger approaches in general are low probability. It's unknown if she's in the market for new romantic prospects when she's in a non-bar venue. In a bar, there's at least a decent probability she's considering new options. More unattached people spend more time in bars. I say these sentences as a man who prefers non-bar approaching to bar approaching in general, but this is a downside of non-bar approaching.
In non-bar approaching, including at bookstores, I can always open with a situational, observational opener. It's no different to me at the grocery store, bookstore, the mall, the general gym floor, or outdoors. I can have a more specific opener for fitness classes at gym but even after fitness classes, I might use a situational, observational opener. While books in a bookstore is a natural topic of discussion, it is no different than something in her grocery basket at a grocery store or something she's looking at in a grocery store.
many bigger bookshops have a 'sit down' area, where you can have quiet conversations
many bigger bookshops have a coffee corner where you can invite a reader to join without leaving the shop (low threshold instant coffee date)
A lot of the Barnes & Noble locations have a coffee shop/coffee corner in them too. That's no different in the USA as compared to the Netherlands. One location of that small regional chain I mentioned also has some sit down areas.
I don't like coffee dates in general but if I met someone good in an aisle or sit down area of a bookstore, an instantaneous coffee date could be useful. Coffee dates tend to be difficult for escalation and the environment in them is a less sexually charged environment. I want to be associated with a sexual vibe.
Some men are also good at picking up in the coffee shop section of a bookstore or in standalone coffee shops in general. I'm not much of a coffee drinker, so I've never had good coffee shop game. I also haven't tried much of coffee shop game.
women who read books are invariably higher in education and intelligence
This can be a good thing but I strongly believe that education is overrated in romantic partners. I don't find I'm compatible with women with advanced degrees. Women with advanced degrees are often less feminine and more career oriented, which is not what I desire. There are some exceptions to the rule with advanced degrees but they are very difficult to find. I prefer women with a bachelor's degree as compared to an advanced degree. I either like to date women with a bachelor's degree or non-bachelor's degree holders with a good trade certification. Many 'medical assistant' type women do not have bachelor's degrees but simply have a medical trade certification.
Intelligence isn't always related to having a bachelor's or advanced degree. I do like someone who can carry a conversation and has some level of intelligence. I am fine with dating women in the middle of the bell curve of intelligence. When considering intelligence, most women fall in the middle of the bell curve. The people at the sides of the curve (most intelligent and least intelligent) tend to be mainly men. Female intelligence clusters whereas male intelligence has a wider dispersion.
conversations are not viewed in general as seduction, so you can easily meet and talk with women without looking like a player.
The whole "looking like a player" thing is overrated. If a man is good looking enough or rich looking enough, a woman won't care too much if he "looks like a player". Bookstore approach conversations are pretty ordinary, as are most non-bar approaches in general.