I haven't had any problems with cars, though my cars old enough to have carbs only get occasional use. The automatic fuel cutoff on my riding mower stopped working and I installed a manual valve. Seeing as how it's over 20 years old that could have been normal wear, it runs fine otherwise. Worst has been my gas-powered string trimmer. It's been a real challenge to keep that thing running. (In general small two-stroke engines seem to be affected worst by ethanol contamination.)

It keeps fuel systems cleaner

One reason I think that gets people on this topic is that ethanol gas doesn't "sit" as well as non-ethanol gas. It deteriorates faster, so those seldom-used cars or lawn mowers and the like stop starting reliably because the gas has deteriorated. I never had to use fuel stabilizer until ethanol was in the gas; now I use Stay-Bil  or the like on everything except my daily driver and have had good results with even 6-9 month old gas.

All my engines use E0, no ethanol gas.  If you have to use ethanol blend in small engines, you might want to put an additive in the tank to keep the gas & alcohol from separating over time.  Alcohol has been known to attract moisture so you may find evidence of rust in your tanks and fuel lines if your lawn care engines have been sitting awhile.  Marine engines are especially vulnerable to moisure.  You'll find numerous fuel stations with E0 fuel available around the big lakes here in Missouri.  Moisture from E10 fuel can attract water into boat engines, cause them to rust over time and bond the piston to the cylinder wall & seize. Some states allow no ethanol to be sold as regular octane.  Missouri no alcohol fuel must be sold as 91 octane or higher.  I heard alcohol in gas can clean fuel lines & engines.  I run a can of injector cleaner through my fuel system at every oil change anyway.  I see ethanol as fuel filler to help agriculture sell their corn.  http://www.pure-gas.org