From the article:

Yes, so you can honestly work multiple work-at-home jobs at different times & days,” she says. “I would DEFINITELY not recommend working all 4 full time at the same exact time.

Well then

a) you're not making $60/hour, you're still just making $15/hour and just extending your workweek

b) this is not working jobs "at the same time," this is called "moonlighting." There's a long history to it and most employers don't have a problem with it as long as it doesn't affect the hours they've set aside for you