[andybak]

> - I don't want an untrained barber spreading disease.

This is a fairly weird statement. For a start conflating "unlicenced" with "untrained" and then jumping to "spreading disease". I'm not sure catching a disease has ever crossed my mind while getting a haircut.

> - I don't want a fake optometrist selling incorrect glasses.

The fact that they are "fake" surely already implies fraud - so how does licencing prevent this?

> I don't want someone buying penicillin off Amazon to treat their flu, or taking it for 2 days and then stopping so that they incubate a PCN-resistant strain of whatever.

People already do this. I guess you're arguing against increased incentives but that's a bit of a leap.

[leetcrew]

I'm not sure barber is a good example of a profession that absolutely needs to be licensed, but it's worth noting that they use implements that a) can nick you, and b) may have nicked someone else recently. there's at least the possibility of blood-borne pathogen transmission (though likely not HIV).