Having a central box doesn’t work everywhere.
When it’s 110 degrees in Las Vegas, you won’t find it easy to walk two blocks to check to see if the mail has arrived; and
whatever is put into those metal boxes is going to be roasting at 150 degrees or more.
Real reform is
1) letting private businesses (like an office supply store) handle routine over-the-counter transactions. That means their employees, not USPS employees, do the work (reducing the number of USPS employees).
Let most junk mail be sent by email (you can print out the coupons you want). The USPS can charge a fee for the emailing—almost all profit to the USPS, for very little expense.
Mail men should only deliver express $$$ mail.
There shouldn't be very many carriers.