Hong Kong is small. But 30min is exaggerating it a bit for Tung Chung To QMH. Even Google Maps directions gives a route that takes 37 min, not considering traffic.
If you consider the worse case scenario in terms of traffic, just making it across the tunnel could you take you over an hour (ie, what if you're water broke during morning rush hour on a weekday?).
You should also keep in mind that if you call an ambulance, they will not take you from Tung Chung to QMH. They'll just take you to the nearest public hospital.