I've never seen anyone walking in Brighton town centre, UK, in swimwear or having sex in public space during summer.
It is not illegal to have sex in public in the UK, unless there are two members of the public witness it.
~ In Thailand, it is not acceptable and illegal, yet many tourists think, they have the right to do it because they are tourists, spending money in Thailand.
~ Tourists in Europe spend a lot more than in Thailand, with this kind of reasoning, they should have the right to do anything they like. Shouldn't they walk about naked in the Buckingham palace and have sex in the British museum? Why don't they? Is there something they respect? Why is it OK in Thailand? Is it a lowly country?
~ You are in a foreign land. It'll be wise to learn about where you are.