they care enough to make psp homebrew damn near impossible, f.e. changing firmware every couple of months.
And how exactly does "changing firmware every couple of months" make "homebrew damn near impossible", if I may ask? Those updates aren't installed automatically or anything.
Only problem there used to be was that every new unit had "newest at the time of manufacture" firmware pre-installed (for a while the "homebrew maximum" was 2.0, being the highest version capable of running rather limited homebrew and -more importantly- being downgradeable to v1.5 which is kind of "unofficial standard homebrew version")
Nowadays you can downgrade from much newer versions than 2.0.
What you might say next is "new games require new firmware", which is (kind of) true.
"In the old days" people were hacking iso images of games, replacing files from older 1.5-compatible games. That way you could get an iso image of a game running on 1.5 from memory stick. Nowadays there's this wonderful "anti-piracy tool" called "Dev-hook" that can run newer (upto 2.71, which indeed is "quite new". Additionally many "if version
I recently bought Guilty Gear XX & Judgement from the US (games aren't region coded) and it "requires" 2.71, yet runs just fine on dev-hook. Of course I wouldn't have bought it if it would not work :-)
Of course Sony is trying to prevent new games running on not-really-"upgraded" PSP's (and homebrew-users from buying the said games) but they have been failing in doing that for a long time. Already 1.5 was supposed to be "homebrew-proof", but it most definitely isn't.
It's not that they're not trying to prevent homebrew being ran on PSP, it's that they're totally failing in trying to do that.