I can understand the face mask policy for better or worse if it is an indoor restaurant where you are standing in line and paying for services, but drive thru should be different. Drive thru windows are outdoors where there is a smaller chance of infection. However people want to try and conduct business in a ‘safe’ manner as possible.
If infection rates are low enough in a county or state, we should gradually pare down guidelines. Right now covering the mouth might be one idea that would be an option.
On other related issues about the over-caution about the ‘rona’, the six foot rule seems absurd. There are even MIT researchers who state that the six foot concept seems very arbitrary. Reduced occupancy might be the better option than a six foot rule.