NuName and others...
Totally agree that one does not want to wear attire the boss is opposed of. My boss could care less what we wear, just that we get the job done safely and efficiently. I have been in the part 91 owner world for many years but flew 135 jet charter prior and even then wore business attire....no uniform. No problem.
In the US the majority of uniformed guys you see are employed by NetJets and the like. The pilot uniform is a must in this environment for standardized look and to satisfy the variety of pax they service.
Again, I have seen no advantage to wearing a formal uniform in my travels but I don't work in an environment where I am left on my own to navigate my way in and out of foreign airport terminals...always with an escort. This admittadly is a big advantage.