I would have thought banks prefer to lend money for buying houses because they get the house as a security (if the lender can't pay up, the bank gets the house)

I would have thought banks prefer to lend money for buying houses because they get the house as a security (if the lender can't pay up, the bank gets the house). Presumably the notion that houses are relatively stable investments lies behind that notion, but still, I don't think it is just a whim of policies. In any case it seems easier to judge the value of a house than the value of some random stock, which might also be something banks like.