TBH you're most likely the problem. It could be an energy thing. Get to a point when you don't care about cancellations, don't be salty, just let it be. Let her reschedule, if not its dead. Don't be too excited before a date too. Don't imagine yourself on the date too.
I know if you're talking about principles, and you're like me, you rarely cancel and are always on time. I understand your viewpoint.
Sounds insane, but desperation often smells.
More often than not she got a better offer. This is why you need to use the one strike rule.
It's not likely an energy thing, it's more a value thing. Every woman wants a high value man, and many bet on the 1/256 chance one will approach her next month. And we all care about cancellations, actually getting with the girl, and winning (getting laid). Let's not kid ourselves.
Many things are out of your control between the approach and the actual date time. No different than a job interview. The woman has the final say-so. If this is a 8+, and you're not a HVM, it's a 1/256 chance she chooses you for an alpha role, 1/8 chance for a beta role. We're always competing for a date with any given girl. No guy wants to be home alone on a date night sitting in front his Playstation 5 unless he's getting paid to create or program games for it.
Point is, expect the worst. Most guys are invisible to women. She can't feel your indifference. She might flake because you won't be beta. Or you're too alpha. Or because you use Samsung instead of iPhone. Or you cheer for Ohio State. Whatever the case, drop her, and send her a pic of you and a new girl (provided she's hotter and sees you as alpha).
Maybe we should be flaking on chicks first.