The bribe here is not to people but to the government. If the tax effect for the city outweighs licensing costs it makes sense for the city to switch. The city where their office used to be is the one suffering under the decision.

The bribe ends up in your pocket, the credible alternative only serves the general public.

> That only makes sense if the total bribe outweighs the investment in building the credible alternative.

It only makes sense to take the bribe in that case. It always makes sense to prepare for the switch, because if they won't bribe you enough to stop then you can always actually do the switch, which is still better than the status quo.