Yes, and think of the quickie lube example you bring up. If you were to have the following service done to your car, (which I have done on my service van for $24.95 in 15 minutes or less, with no appt) how long would it take one person to do:
supply material and have it ready to go
change oil (underneath and above vehicle)
lube chassis
check for leaks
top off wiper fluid
check tires (air and wear)
clean exterior glass
check lights
check air cleaner
check tranny fluid
check antifreeze
vacuum interior
compose bill
take money.
Hmm, I'm pretty handy and do as much as I can on my personal vehicles, but I'd be busting my hump to do that in an hour. In that situation volume is how they get by, replacing air filters, bulbs, tranny flushes, diff lube and other *EXTRAS* are where they make money.
Now, with plumbers... It is customary to be billed for apprentices/extra man. I will tell you right now as a plumber that nobody is just 'dead weight' when it comes jobs (and if they are they don't last long). The extra man was most likely getting stuff from the truck, cleaning fittings, learning whilst being productive, cleaning up, etc. Without that ancillary work, the job time can increase twice easily, if not more.
Additionally, we don't have the luxury of having transporters like those space guys on tv. We still have to come to the work, and go back to where we were (like to see the quickie-lube guys do that). Just getting to and fro is a larger and larger cost nowdays.
$186 canadian, yeah... that's a good deal!