It's not simply that they don't have any requirement to consider fair use but that there's no incentive for them to do it. If they defend users content that may infringe or may be fair use (the distinction is up to a court, mind you) they open themselves up to secondary liability. If you're a service provider you're probably going to err on the side of claimants and never reject a single one.

Yeah that's the whole point of DMCA, you remove liability by not taking side.

If youtube's automated system detects a copyrighter (eg.) song, the user should be given an option to say "no, it's not copyrighter, or it's fair use, etc", after that, the claim should be forwarded to the copyright owner.

The copyright owner would then verify if it is indeed a copyright infringement, and if they believe it is, and the user still believe it isn't, the case should be brought to some quivalent of "small claims court", where both sides would present their sides, and the loser has to pay some fine (not too large, but still high enough to deter pointless cases.. eg $1000 (to cover the court cost), and damages up to eg. $1000 due to lost views, or damages due to unlicenced distribution).

Basically, make it worth fighting for, if you're sure you're right in what you're doing, and not too expensive, when eg. Sonys lawyers build a multi-year case, destroying you financially, even if you're doing the right thing.

Well, that sounds like something to take up with the legislator, not YouTube.

From another non-lawyer perspective, might it be different since there is money involved? I view it as potentially infringing on some people’s livelihoods.

Again, just spitballing. I have no idea what the reality of the situation is.

part of the issue is that fair use is something that needs to be proven in court