You are just one of the unlucky ones. Most people never see a failure or at most 1. After working on mowers and engines for over 25 years every engine manufacturer has their quirky engines. For me the engine brand that is the most troublematic is Kawasaki. But that may just be due to the engine keeps running or the customer ignores the problems until it won't run.
My most common issues I see are ignition modules, carb issues with either the float valve not sealing or engine surging, and stator and regulator issues. So what happens most of the time is the customer brings in their mower and it is running on one cylinder, surging and not charging. So I may need to repair all 4 items in one shop trip.