Why such a high markup on installing a tankless water heater?

I have a Rheem gas tankless water heater that is having issues. I’ve ask a few places to give me a quote to replace it with an identical unit. The heater is in a partially finished basement with excellent access and all the piping/wiring is in good shape. Both companies said it would take about 30 minutes to an hour, as it is literally unscrew water/gas/vent, change unit screw back in. Both said that all the piping can be reused as it’s in excellent shape.

Yet, both companies quotes were between 7-8k. The exact unit is $1500. I don’t mind paying for work, but 5-6k labor for less than an hours work? I’m in Seattle, so that doesn’t help, but the price seems high regardless. What am I missing?