Get a power bank. They are cheap and even the large ones weigh no more than a pound. They have enough juice to get any phone through a day or 2 of use. You bring it with you everywhere and you never have to think about the battery level in your phone. Notice it's low (single digit percent battery) while out and about, plug in the powerbank and carry on being out and about.
The idea that I would use a public charger attached to a garbage can that I would then need to sit next to for an hour is crazy.
A few years back there was a startup that had kiosks in grocery stores to charge while you shopped (locked into a little cubby hole), but those seem to have disappeared too.
You're anyway stuck in your seat and chances are good that you're low on juice during a day of traveling.
Same goes for trains. Alas, they usually have power outlets.
Given that my boarding passes, train tickets and other vital information is on my phone having power is essential.
As a light traveller I don't want to schlepp an additional gadget.
To each his own, I suppose.
If you let the phone display the prompt, you might infect a couple people but somebody will soon tell the shop staff, or even the police.
If you have a zero day then you are probably targeting some particular people, let's say diplomats, protestors or attendees of an important international conference. The chances of the average person being a victim of these attacks because they charged their phone at a cafe are negligible.
Many airports, planes, and other public areas have these USB charging ports. Either people are using them, or a lot of money is being spent for no reason.