Google probably works because you have it set to use ssl (https:// instead of http://) which means it is using port 443 and the packets are encrypted so they cannot use packet examinations on select ports to determine if you are tethering. Some mobile providers, including at least metroPCS and T-Mobile, use this IPE to block tethering both over wifi and USB
One workaround for this problem, if it is in fact the cause of your problem, is to use Chrome on linux, or set your user agent to the one for Chrome on linux:
"Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.65 Safari/537.36"The reason this works is because Android uses Linux user agents, so they cannot block those, or your browser on your phone wouldn't work either.
I did a quick search for you and found a page on how to change user agents in various browsers HERE.I'm not sure if that page is up to date/accurate but it could be a place to start, or a more precise google search for your specific browser might give you a better result.
Hope this helps!
