Some people route Tor through a VPN to stop their ISP from seeing that they're using Tor. In order for the ISP to know, the VPN provider would have to tell them. You cannot trust the VPN provider not to do this, but if you use the right VPN service it's less likely than with others. Other people route their VPN through Tor so as it's impossible to see that they're using a VPN in the first place, but everybody has their own reasons for their own security setup. ISP's will likely try to spy on their customers more in the future but that is why we have to fight against this internet oppression!! Libertas