They only approach the cars when the light is red and generally because they have been waved over by someone who wishes to give them a donation.
I am not sure what "frustrated commuters" would be all upset about as this does not delay anything and traffic is very light on labor day.
They do this in my hometown, but the firemen stand in a median, not in the street.
Same thing here. Our firefighters do a ‘fill the boot’. They stand on the sidewalks holding the boot up and will walk into the street to the car to get a donation when waved to. Usually the person in the car already has their money out to drop in the boot.
Since hubby was a firefighter (retired now) I have helped work our ‘fill the boot’ fundraisers. We have one coming out that I’ve volunteered for.