Australia is about to start a professional women's baseball league in about 2 years. In the same news report it said that the US doesn't have one. I am amazed. Why?
Women in the US are usually pushed into softball, for starters. Otherwise, US women professional sports leagues have had a hard time surviving. Women's soccer sees an uptick every time the Women's World Cup rolls around but still trails MLS which fights for its own recognition, the WNBA relies heavily on the NBA propping it up (and even then most players have to also play in Europe to make money) and women's hockey is a mess.
There is women's baseball. However the answer why it will not be a "paid sport" is that it highlights the disparities in the human body between the two sexes. In simple terms adult women would not only be really really bad compared to men they would be really really bad compared to teenagers. If women could play this sport at a closer level it would have happened (I am not counting one-offs just to watch women).
- the fastest a woman has ever thrown a baseball is 69 mph. Nolan Ryan was clocked at 108 mph. That is almost double! By the same standards the fastest 400 meter dash by a man is 44.5 seconds and a woman is 47.6 seconds. Pretty close right. But if you extrapolate the throwing speed and use the 400 meter dash a woman's best time would be about 69 seconds! Would anyone take that serious? Just for thought I have a 9 year old that can come pretty damn close to 69 seconds.
- swinging the bat hard enough. In fast pitch softball they still use metal/composite bats because wood bats would need to be swung harder. This would be multiplied in baseball as you need to hit further distances and would need a bigger bat.
- throwing to bases. This isn't how hard but how far too. You would have issues with 3B and SS making long throws. Basically you would see issues with slowly hit balls down the line that are routine outs - super easy outs - this would be analogous to 10u kids baseball.
Example: When I was in college (D1 school with bigtime basketball) I played a little bit on the practice team - when they had many players hurt. The summer before my senior year the WNBA had tryouts at our school and the players stayed in the dorms. There was about 25-30. I played pickup ball against them for about 2 months with some stragglers at the rec center - so older guys, decent younger players, and a couple like me that got a little practice team time.
In two months any team I played on never lost a game to the all possible-WNBA players (to 21 by 1s and 2s) - zero games. But there were close games, the girls were rough, and generally kept up. They simply couldn't stop a hard drive. If I put my head down and split two players it was a bucket. But the games were close 21-12ish would be average. These weren't the WNBA stars but your bench is getting beat by college kids but its close.
Baseball however myself and two teammates were throwing mid 80s in high school. Probably threw 69 by freshman year. So the competition level for women's baseball is maybe JV high school boys level. Where the competition level for WNBA (with their best players) is probably close to DIII college. That is a huge huge difference.