The size of the country (relative to the population) means that land is relatively cheap. That leads to relatively less dense cities (at least most of them).
Land isn't cheap if you have to maintain infrastructure around it. Exclusive single family zoning is a pure loss. Single family housing should exist but it should be reserved for those who really want/need it. It's not something everyone should have because it doesn't match people's real needs.
Sprawl isn't a natural result of a large country, nor is US land unbelievably cheap (it's all over the place, with some expensive peaks in some high-sprawl areas).
Belize and Norway are extremely low density overall in their countries: they have very different house prices, but neither has much sprawl.