It is in the UK cos there's a great law about it. In other places it's often near 80% of the pint cost for a half, which is a crazy rip and encourages drinking more.
Edit. Googling this I can't find that it's actually a law, must be just a very good historical precedent
I always check how much a half is in comparison to a pint and friends always say I’m stupid because of course it’s half the price. But I’m sure I’ve been places in the UK before where that hasn’t been the case.
I've never paid attention so... is a half of lager half the price of a pint of lager?