Closing post offices is a political issue. It should be a business decision.
The federal government is too big, as most of us agree, cutting an out-of-date money losing service would go a ways toward government efficiency; and I would hope it might start a trend.
People quit paying bills so creditors quit sending them bills ~ thereby cutting costs. Folks without money don't buy stuff so advertisers quit sending them advertising.
It's all quite logical and not at all a problem with technology.