Twice as often? Hardly. I doubt anyone on this forum even if you were a commercial user would be able to tell the difference in engine life between 40:1 and 50:1, especially if you use a good oil like Red Armor, Amsoil, Husqvarna XP, Opti-2, etc.Emissions.
I wonder if the man ever bothered to figure 50:1 but your replacing stuff twice as often. They probably looked at tail pipe emissions and figure "meh the engine won't immediately fail on that little oil".
Not sure where you guys are seeing landscapers running 32:1, I have a few commercial landscape customers and they run Red Armor, Supertech, and Husky oil at 50:1, and two of them run Amsoil Saber at 80:1. The recommendations back in the day for 25:1 and 32:1 were from when you actually mixed SAE 30 motor oil with the fuel. 2-stroke oil technology has progressed lightyears ahead of those days, and all equipment is designed with 50:1 mix in mind.
The dirt bike guys run 32:1 and 40:1, but that is because more oil = leaner air/fuel ratio and the engine can make more power. It also means it will run hotter, as fuel is important for cooling in a 2-stroke. You are way more likely to blow up a 2-stroke engine from your carburetor tuning being too lean than if you run 50:1.