I should have been clearer, I didn't mean 100% national coverage, I meant at whatever service area they choose, they need to cover 100% of what USPS covers now. For example, if they choose to cover a given ZIP code, they don't get to decide certain cul-de-sacs in that ZIP code are outside their coverage area.

And we absolutely do place similar requirements on new entrants in monopoly enterprises. I'm thinking about things like 911 service on cell phones/VOIP phones. Basically, we all need the "new mail" to work pretty much like the old mail it's replacing. It's in nobody's interest for an inferior system to eat all the profit and drive the existing system into collapse.