These two quotes could and should be picked apart and dissected. Very misleading and uninformative. All depends on location and what you plan on washing. There is many facets in pressure washing where 8 gpm would be counterproductive and an unneeded expense.
But I am on vacation with terrible phone reception half the time. Maybe in a week when I can sit down and type it out on a laptop.
You’re right. But the difference in the two is apparent in how much you can schedule and complete for each day.
Also, once you’re above 4gpm, you’re pretty much destined to buy a trailer (or flatbed/utility bed) so you can put down a larger buffer. But I agree with most everything else you said
Everyone has their own needs. I did both and if I had my 8gpm all throughout 2019 I would be thousands ahead right now.
When I started I got the minimum to do the work and collect a check. I saved saved saved every penny, put side money for taxes. Talked to a CPA after one good season of part time washing I earned the ability to get the best equipment for this field of work that will improve the level of clean I can offer and be more efficient. Time = money. I’ll be building it over the off season and keep you all updated on the build progress once I’m ready to start building. Parts already ordered 
Christmas in November !
My point is to start within your means and save. Be money smart
