Nevertheless, I can't understand why someone would open a cafe in 2007 at a site that wasn't compliant with a 1990 law without budgeting for bringing it into compliance.
Wait, why? Certainly one would expect that a lawyer might have a specialization, say, ADA compliance. And you'd equally expect that a person in a wheelchair who is more likely to notice/care about ADA compliance.
It doesn't strike me as that odd, it just seems like, "Hey, why is the city I live in so busted for me? I thought there was a law that was supposed to give me access? Why is no one paying attention to that law?"
Lawsuits require standing, which is defined as basically injury or adverse effect done to the suing party. Without that, you cannot sue(and expect to win).
And the opportunistic part comes in because these lawsuits are almost always "Fix the problem for $5*X, or pay me personally $X and I will drop the suit".
I would guess the opposite, that 200 buildings seems low for what a person might encounter in a year that failed to be accessible. That's basically saying, "It's a roughly 4-5 buildings a week" which absolutely seems in the realm of possibility to me. Especially in a older part of town.
Nevertheless, I don't have a lot of sympathy for the business owner in this case. If you open a business in a non-compliant site 17 years after the ADA went into effect, and 13 years later still can't build a ramp, it might be time for another business to occupy that site.