They may tell you that those people consistently buy enough to justify their discount-Regus space and they may tell you that those nerdlings are holding tables for the groups of coworkers who rotate in on an hourly basis.

They may also have no idea that it's causing a problem because they see acceptable revenues.

Be more aggressive in asserting change and you'll feel a lot better. Just asking the staff or the shift manager will let you know if it's an easy problem to solve or if you should probably find a different place to hang out.

Coffee shops have become workplace annexes since at least the mid-1990s. I like to take meetings in them because the risk of being overheard regarding internal politics is reduced, it gets interviewees a chance to refresh while you get to know them, and frankly, we all need the walk sometimes. A cup of coffee is also a good unit of time. You may need to wait five minutes for it to cool to a drinkable temperature (I'm a quaffer), you'll take sips from time to time, and you'll eventually finish and have an understanding that something is at an end and a change should be made. In this case, it's throwing away your trash and de-assing the place. :-)

(And if someone has the iron butt to sit in those chairs in your photo for 4+ hours, the muscle and nerve soreness should be motivation enough to go someplace else.)

There's probably some price where the cafe would force people to move, but you haven't spent enough yet. I can't tell if you're mad at the cafe for not honoring you for spending money, or if you're mad at the people with laptops for existing.