I also worked polls in Philadelphia and we were also visited by non-uniform cops at the end of the day to do the (critical!) step of picking up the paper ballots. We got their badge numbers and names of course, but it was a little sketchy. The one who came by midday was uniformed, though.
Here in Boston our officers were in uniform all day but they told us they drop off all the ballots out of uniform in their own personal vehicles, he surmised to be less obvious a target. I thought it was an interesting approach, perhaps not super effective but interesting.
Very interesting. Is it possible they were constables? They are very hit or miss, on uniforms and other aspects. Not sure if Philly has constables or not.
Part of the constable's duties is to open and close the polls. I'm not sure if they're required to be there the whole time or not. Our's is usually there. Sometimes he is in uniform, and sometimes not.
In some jurisdictions --- I don't know how common this is, but it's the case in mine --- uniformed police officers are prohibited from the polling place unless requested by election judges because of the potential that it will create a voter intimidation situation (keep in mind that these law enforcement officers are under the command of one of the people on the ballot). So I would conjecture that some areas may ask police to appear in plainclothes, although here police are simply not present at all unless requested---the county did hire a private security firm to keep an eye on some locations though due to problems during early voting. This is basically because the right to eject someone from the polling place rests with the election judge, not police or security, but they're temporary employees and not trained in deescalation.
