Seriously, what's the logic behind bills anyway?

I've always figured two things: if you own expensive items, insurance for them is included in the bills (not government bills but still bills). And if you have too many items in the household inventory, it's a storage fee.

Sure, the bills don't make complete sense when compared to real life but I don't see it as that much of a big deal. Have a Sim do the Fabulously Wealthy aspiration and the deposit/interest pays for a big portion of the bills.