It's extremely bizarre, don't know why everyone's trying to make out it's normal to paint your drive bright blue
Some people don't actually care about doing things the 'normal' way - they do what they like and don't care if others like it or not. If doing what they like is illegal or antisocial, that's a problem, but if it's just painting a part of their home an unorthodox colour, it's nobody else's business.
There's an older lady in our town who dresses every single day in very ornate black Victorian-style garb - just like she was on a tin of Quality Street - even just to do mundane things like her grocery shopping. She knows that she isn't complying with any current fashion/clothing norms, but she doesn't actually care and dresses like that because she wants to. Nobody else's business whatsoever - it's her choice; if anybody laughs at her then they're the ones with the problem, not her.
Yes, the landlord might not like it, but he might have already asked for permission and been given it; or be prepared to strip the paint off or repaint it grey or black upon giving (or being given) his notice. In the big scheme of things, it doesn't really matter.
I feel really sorry for people who, because they can't get a deposit together, are trapped in having to pay far more each month in 'dead' rent (to pay somebody else's mortgage on a considerable investment) than owners pay for a mortgage for a comparable house, and then are expected to live so gratefully as though they're being done a massive favour by being allowed to live there and shouldn't be able to do anything whatsoever to make it feel like their own home.