Banksy is old. Probably in his 50's now? And self-reportedly he has been doing art since he was 14, working in the underground scene in Bristol. That is very load-bearing, those are the kind of artists who tend to be committed to their bit.
You ever see Another Brick In the Wall, the movie? It has all those animation sequences, and they are very blatant, right? Gonna portray the Thatcherite movement as goosestepping hammers:
They are Nazis, we get it. It can be very r/IAmVerySmart, it rubs us wrong way. But that is because you have seen art like this your entire life, today it is political cartoon pastiche. But this movie came out in 1982! Was this symbolism really that ubiquitous in British media under Margaret Thatcher in 1982? It existed, sure, but it wasn't overplayed then. Being nakedly political with art was still very much The Culture of the time, there wasn't this sense that you even should be subtle about it.
(How crass would linking my essay on fucking Gainax tokusatsu films and the left politicos at Japanese sci fi cons in the 1980's be right now? Too crass, I won't do it, but I am not above wagging my eyebrows at it like this at least...)
Bansky started doing art right around the tail end of this era, the post-Bono "Live Aid" art-as-direct-action era. He did typical art of the graffiti era, for sure - and then he also did political art, he did both:
And then for whatever reason the shit on the right blew up and made him insanely famous. Most people don't change that much? Certainly not when they are get insane fame by staying the same. He was Bristol rebel who trolled the police back when punk scenes trolling the police was "good" resistance art, he paints like his influences who thought subtlety was for chumps, he authentically likes the style of graffiti art that was dominant in the 1980's and 90's. He didn't change, you changed, he is just what he has always been.
I certainly don't give a shit about him, change is fine. Just, in the tradition of Extremely Tepid Defenses, he is someone a little out of time - he isn't quite as cringe in his era. And failing to adapt to the times is the default state - that bell will toll for you too, I am quite sure.