Billions of addresses might seem like a lot, but every IPv6 network has at least 2^64 addresses and it doesn't make much sense (to me) to give any customer less

Billions of addresses might seem like a lot, but every IPv6 network has at least 2^64 addresses and it doesn't make much sense (to me) to give any customer less than one network. (Maybe you meant billions of /64 blocks? ISPs could be providing a /32 ≈ 4 billion /64 blocks, though there still are 2 billion of those in the entire IPv6 space)