Everyone has to discriminate where they spend their limited attention. People act like you can't do it but the reality is you have to, dozens of times a day. Even hundreds. There is an overload of people and businesses clamoring for your attention. And there is simply no way to satisfy all of them. Similarly there is no way to give all of them proper weight. Just think about your raw, unfiltered, email inbox stream. Messages are treated very differently.

So we develop shortcuts to quickly decide where to spend our limited resources. They aren't rigorous or fair. There are too many to even be able to do that. They are cursory and quick by necessity and follow our likes and interests.

One bad experience can shape the exclusion of whole groups. Poor speller? Nigerian prince? [Delete]

This discrimination isn't wrong. The asker is the one who is imposing and the recipient is not obliged to satisfy. Even if their filter is completely illogical or even racist.

When it comes to judging people or limiting access to our markets and public spaces. I agree that such shortcuts should not be used. This is a realm where such shortcuts are inappropriate.

Conflating the two doesn't help though, like there isn't a place for discrimination at all.