Actually, H1B already addresses that. H1B is based on Labor Condition Application (LCA) which is location specific. If the employee changes location (even for the same employer), they are required to file an LCA with USCIS (They don't have to go through the whole H1B process). However, this rule is very poorly enforced. I have personally seen cases where USCIS has rejected the H1B renewal if they found out that you changed your location without filing a new LCA.