There is a big difference in quality levels. If you want a good mower pay the price for a commercial mower, people who use them 8 hours a day need something that lasts.

30 years ago a friend of mine did the mold for a lawn mower. They put an engine on it and it ran for 120 hours before the deck failed. It took 7 more tries until the deck failed after 80 hours. Commercial mowers are expected to run over 1000 hours.

Counter anecdote, I've had gas mowers survive decades and EV electrical equipment (in this case, a chainsaw and a battery pack for a mower) both die within 14 months of purchase.

almost all 2-stroke engines have had plastic flapper valves and a plastic fuel pump for as long as I can remember.