Many people have to go to work early without being able to perform Fajr at the Musjid with Jamaat.

Answer

Obviously, these are such people whose Imaan is very weak. The minimum expectation is that they should perform Fajr at home before leaving for work. If there is a Musjid near to their workplace, they have no valid excuse for absenting themselves from the Zuhr Jamaat. If there is no nearby Musjid, they should perform Zuhr at their workplace. There is no valid excuse for abstaining from Zuhr Salaat.