This is purely a standards problem. The working group had to say "you don't get the logo unless you do PD" and have logo. They waited a DECADE to do that, which missed the boat, and when they did it they focused on transfer speed and wattage markings instead of a single stamp.

Is it? DC barrel plugs look identical to most users. Just like USB C. Only one of them negotiates the correct voltage by default in most cases.

This is a non issue, IMO. Does it depend on the electronics being designed correctly? Sure, but that’s the case for all electronics, and most devices probably build on some widely-available standardized control boards from 3rd parties.

As a user, I’m sooo happy that I can bring a portable battery and a wall charger, and both can recharge every single one of my portable devices. From gaming handhelds to large, powerful laptops, to wireless earbuds, to cameras, to smart watches, to flashlights. All with very different power requirements.