Depending on the agency, so-called 'field-based' crime unit members, detectives, etc. might not answer collision or barking dog calls, they are still doing their slice of day-to-day police work, just in suits and unmarked cars. If I hit the little red button on the mic because I'm rolling in mud with some miscreant and losing, I expect everybody who reasonably can to show up equipped to play. The excuse that you are wearing a suit or enroute to take a statement on a bad cheque won't carry much mileage with me.
Trust me, the question of how a suit be expected to carry all the U-of-F kit has been asked, but risk adverse policy makers and departmental counsel stick to their guns (!?). The end result is many p/c members carry what they feel is appropriate and (hopefully) have the rest in the trunk.
True UC members are, in a sense, living a lie - for a living. They take on a non-police personae. It takes a particular personality and set of skills I never had. So-called 'old clothes', street crime, etc. members are somewhere in the middle, but less immersive or infiltrative.
The statistical reality is, in Canada, the majority of members will go their entire career without firing their weapon 'in anger'.