Why can some devices ignore the USB 10uF inrush limit?
For the same reason that many devices ignore the requirement to enumerate and ask for more than 100mA of current.. because they can get away with it (most ports will work okay even with a big capacitor on there) and since there are lots of devices that ignore the 10uF limitation, then the computer designers have to make their ports work or face a lot of complaints from users about their crappy USB toys not working. 

Your assumption that these work "without any problems" may not be correct. They could have problems with a minority of available host ports and not be overly concerned about that.