> For a photographer in question an "expensive court battle" is an obstacle just the same and I have nothing against a lawyer who makes a living out of cases like this.

That this is an obstacle for the photographer is exactly the issue. The scale is required in order for it to become a "practice area" (as opposed to e.g. a pro bono case taken on the side), and the shady practices come with the scale.

I don't see how making a living out of professionally defending independent content producers automatically translates to sending scam e-mails. Both can be done at scale but they are not the same.

Are there actually lawyers who make a living out of the former though? To not have it be so many letters that haste is inevitable, they would have to be individually large claims. Minor violations by large entities aren't worth much, major violations by small entities aren't either (because they can't pay), and major violations by large entities are uncommon because large entities can afford counsel. Meanwhile when they happen they're coveted by every law firm that likes money, so how would anyone secure for themselves enough of those cases to specialize in it?