Men get paid 40% more than women in lots of areas of work, and while I get annoyed about it, I can't do much to change it.
That aside 
I don't understand your arguments, at all.
Sport isn't paid "by the hour" like a job cleaning windows. It is rewarded like most other sports, equally for people putting in effort and competing according to the rules and within the set parameters, and being the best in that category of that competition.
It is not women in tennis who make the rules of the competitions, it is the private organisers and prize funds.
There are plenty of women who want to be allowed to play 5 sets, but they aren't. Same as women weren't allowed to run long distance races until frighteningly recently.
Telling women that they are not allowed to compete over 5 sets, and then saying, well obviously you can only have 3/5 of the pay, is ridiculous. And frankly anyone who says that, or has the idea that females should just compete against males from the get-go and HA where will that get you are coming from a perspective that women's sport is boring/pointless/uninteresting and (often) not worth watching unless they're hot.
It is fucking depressing.
You lot do realise, I assume, that if females compete against males, then that is more or less the end of females engaging in sport. My DD learnt at 4 that "football is for boys" and there is no way most teenage girls would feel comfortable in contact type sports with boys. Due to average differences in size and strength, boys and men would defeat most girls and women. So that's the end of that. What is wrong with the "best in group" idea? No-one is suggesting that different weight classes of boxers compete against each other. Why not?