Sure, but the salary cap (or lack thereof) isn't decreed from on high, it's the result of a nominally market-based negotiation between each players union and the corresponding league. If NFL players thought they could push the salary cap to $200M without killing the golden goose, they'd do it.
I have a hard time calling the result of negotiations between the single cartel of teams and the single (probably less-skilled) cartel of players a market.
NFL salary cap is $155M across 53 players = $3M/player
NBA salary cap is $95M across 14 players = $6.7M/player. But actually it is a soft cap so the teams can spend a lot more in extreme cases.
MLB has no salary cap.