They are not the problem, in my opinion, but they are also entitled to nothing that I do not choose to give of my own volition. Expecting a response, particularly a polite one, to an unsolicited interaction is on the same level of telling someone that "you'd look better if you smiled."

People are free to be in public but must also be aware of the consequences of their actions. One of those consequences may be that they are brusquely ignored.

If they want to be out in the world, go for it, but don't pretend the people engaging in their own activities are the problem.

If someone is approaching you in public with a mic in their hand, you don't owe them anything.

If someone cold-calls you for sales, you don't owe them a moment more of your time once you realize what they are.

If someone knocks on your door to sell knives or pots and pans or Jesus, you especially don't owe them anything.

This is a bait-and-switch; you're saying that the person intruded upon has a responsibility to conform their behavior to suit the person who intruded upon them. The poster above said nothing about wanting to hide from the world, you just made that up and ascribed it to them. You might want to review your approach to discourse.