I guess I have a different perspective. I worked for Stanley Steemer for almost a year, many moons ago. Tips are not required, but if the guys that come out are super polite, go out of their way to keep your house clean and ordered, and especially if they move any furniture for you, it would be very nice and thoughtful of you to knock them an extra $5. They would appreciate it, I’m sure.
The reason I say this is that I worked with some guys who did not give a shit at all. But then, I worked with some really nice, thoughtful guys that cared a lot about the customer and their home, often taking extra steps to be good guests and respecting another’s home, and I personally would tip those guys because that kind of behavior should be rewarded.
Lastly, they’re not supposed to move furniture for you, so if you ask them to and they do, they are possibly breaking company rules. A tip is a nice ‘thank you’ in this situation.
The one caveat is when you’re dealing with the owner of a business; you shouldn’t worry about tipping in that case.