People's interest in the game has nothing to do with the "work" the athletes themselves do. They both kick a ball around. And again, when it comes to RESULTS, at least the women's team in the U.S has much more quantifiable success than the men.
What I would argue as far as "equal work" goes, and how it isn't equal is the level of competition. The U.S women's team is a big fish in a small pond. Not unlike Mexico used to be in CONCACAF when playing teams like Trinidad and Tobago, Honduras, Haiti, Costa Rica and even the U.S were easy victories. Now, however, with these teams investing in their teams and programs, they have caught up and give us a run for our money and on several ocassions, beat us outright. As you pointed out, MEN'S football gets all the attention therefore most of the money, in poor countries or simply in countries lacking the U.S's spending power, where the men's team gets little money (like Mexico, Haiti, Honduras, etc.) the women's team gets even less. I've seen many games of the U.S team play and on some ocassions it looks like their playing against school girls, not women, much less competitive peers.
Compete level aside there is the fact that women's soccer is not as physical as men's. Men's soccer is rough, dirty, with jabs and elbows and kicks to the shin. Women's soccer is much more open, more finesse, they as if they respected boundaries and personal space. So the style is different. I liken it to the difference between North American Hockey and European Hockey. There is a reason the Stanley Cup is the most coveted price and the physical grind it takes to get it is a big part of that.
THAT would be my argument as there not really being "equal work," popularity of the sport aside.