The world is for all real purposes has been gobbled up by the Anglosphere. It's all but dead; I'm sure many people realize how drab and low-entropy our world is today.
It's also rather Anglocentric to assume that the "generic world" you describe is an "Anglosphere". Today's modern aesthetic is often described as Japanese/Zen or Scandinavian, and indeed, its biggest purveyors -- IKEA, Muji, Uniqlo, H&M -- are not from the Anglosphere.
I'm guessing it has to do with the position of the sun relative to the earth / how sunlight enters the earths atmosphere.
Just seeing these more vibrant colors have the effect of lifting my mood a bit.
Just last week I heard somewhere that colors in New Zealand are very vibrant as well. I've never been there, so not sure how it compares to Thailand, but perhaps it's true.
It's because those who need the buildings want them cheaply, and aren't considering an aesthetic factor.
I did a self-build on a house in 2021 and the county planners insisted I had to make the house blend in with the existing ones. There was no room for creativity.
For an age we're we've made progress in personal freedoms we seem pretty hell-bent on forcing conformity.
I live in an apartment that's about a century old, the style of which was widely (but not universally) replicated all over the industrialised world around that time. The view out tall my office window has some other apartment towers in a different and more recent style, perhaps 50 years old, and some short ones in yet another style that might be less than 10 years old.
I suspect that if everything looks the same to you, what you're seeing is the last time a place had major economic growth leading to a building boom.
When it comes to world models, I've met an anarcho-capitalist and an anarcho-communist, and I've known someone who thinks the best thing about democracy is preventing(!) people from getting what they want, and multiple people who want to end technological growth to let the ecosystem (they use the word "planet") heal, and at least one other who would gladly disassemble the actual planet to build a swarm of O'Neill cylinders to power a colonising swarm of von Neumann replicators to do the same to every star in our future light cone. My mother had anecdotes about relatives causing scandals by marrying outside their denominations of Christianity, I've known at the least atheists, Buddhists, Christians, Hindus, Muslims, at least one literal Satanist, and Wiccans (and probably some more but it hasn't come up in conversation).