Free childcare for low income families is extremely common, even in the United States. Subsidizing childcare is even more common. And it's not that expensive, because spending tends to get offset by increased tax income and reduced consumption of other wellfare benefits (from parents who choose to re-enter the workforce).

As for universal free childcare, I'm aware of it's existence in a number of places in Germany (Berlin, in particular), driven by having been an extremely popular public benefit in East Germany.