Can someone explain to me: How is a hiring quota based on race better than one based on class?

Assuming that you think that hiring quotas make sense.

My impression is that "class" or some measure of it such as household income is a better criteria to take for hiring quotas then belonging to a certain ethnical background. I would think that in regions where racial discrimination is a problem, it will manifest itsself in household income anyway. I see no particular reason why a person who is a member of a minority, but has a wealthy familiar background which could pay for their education, when applying for a high paid job that requires a college degree, is underpriviledged in comparison with a person from a non-minority working class background that got that same degree with scholarships.

I have heard people say that making a hiring quota based on class is not as good as race, because generally people of different classes are not competing against each other anyway. It doesn't quite convince me.

I think that's what affirmative action was really doing under the surface, anyways: helping minorities who were in lower classes because of discrimination.

If two people are about equal in every aspect (test scores, achievements), and yet a lower-class one didn't have access to the environment that the other did, they may in fact have more potential if you improve their environment.

are not legal anyway, so your question is sort of moot.

than employers could return to discriminating based on race; ergo, an employer could hire thousands of employees from the poor class, all white.

Your suggestion doesn't solve the problem the quotas are designed to address.

It's an imperfect system, but much fairer than the previous system.