Because though uPVC windows lack the myriad advantages of wood or stone frames, sometimes it is better for the ongoing fabric of a building to just get it weatherproof until someone comes along who can afford to put in more suitable replacements.
Then white uPVC frames are much cheaper than coloured versions.
Why on earth white plastic windows and baby blue paint?
Because though uPVC windows lack the myriad advantages of wood or stone frames, sometimes it is better for the ongoing fabric of a building to just get it weatherproof until someone comes along who can afford to put in more suitable replacements.
Then white uPVC frames are much cheaper than coloured versions.
Can’t speak for the baby blue.