While I'm sure a few people tip, this being China it is not the custom and is therefore absolutely fine not to do so.

Also - just so you know - simply taking a taxi from the airport to the hotel would present no practical problem for an English speaker, and come at a much-reduced cost. On my first visit to China I paid $100 for a pre-booked car to the Hilton, only realizing later during my stay that there had simply been no need.