Ask HN: What stops the USPS from offering everyone an email address?

I have been thinking about this for a while now. Why doesn't the US Postal Service (or Royal Mail, etc.) offer everyone an email address? While they are at it, why not offer digital storage as well, so people can store their photos, files, etc., knowing that the USPS will be around a lot longer than their private competitors. Would less tech savvy people who already use the USPS for mail boxes and other services be more willing to trust it than a tech giant they are less familiar with?

If said USPS email address is linked with physical addresses (updated regularly), then couldn't the email address also being used for address verification purposes when fulfilling online orders? I know how painful address verification can be, and I would have loved to have had a service like that. Ideally all a customer needs to provide an online store is just their USPS email address, then the site can obtain the shipping address from USPS.

Edit: added last sentence.

Edit 2: Perhaps the question should have been: what are the pros and cons of the USPS offering: an email service, a digital storage, etc. Would it improve their finances if they charged for them? Would people pay for them given that there are plenty of free services out there?