Yes, most go to the venue, which the artist/producer would have had to pay for (from the ticket price) otherwise. Because money is fungible it doesn't really matter if they pay the artist, or if they pay for the artist's expenses.

What matters is how much fees they charge and how much do they keep. Can't find it right now, but I remember an article claiming they rarely keep 50% of their fees.

I don't have a source but I've read the same thing; that a lot of what ticket master takes in is getting bounced around. It's a view I find very plausible intuitively. The artists (esp. the "name" artists) have all or nearly all of the leverage - whatever the ticket costs above what you'd paid if you bought at the gate is money they're leaving on the table.

It’s not just Ticketmaster.

Many “event platforms” allow you to add fees that cover the credit card percentage, but if they’re higher you just get to keep the extra.

Generally there's a promoter in the middle. They sign the artist and then have a deal signed with their ticketing partner. They'll then sign contracts with venues for the given tour. The contracts between promoters and ticketing agencies vary a lot depending on the country but that's how it often works in the states.

The "face value" (base price) will usually be determined between the artist and promoter, the venue will apply a fairly generic fee on top, as will the ticketing provider.

How much of the face value goes to the artist will depend on their leverage in the contract with their promoter. This is usually best improved by the confidence that the venue will sell out, meaning artists with bigger audience and social media presence will usually get the best terms.

I don't have a paper or article I can link to as a source, but I have experience in the industry.

That's not at all how concert economics work, I just wrote a long comment explaining.