In the case of lawnmowers, I suspect the use of universal
motors is to make mowers into consumables, which people
will thus tend to change every few years. Just about every
characteristic of a universal motor is inappropriate for
a lawn mower. You can find mowers with induction motors,
but they tend to be in the better quality less well known
makes, which you have to buy from specialists rather than
DIY sheds.




I suspect the main reason there is power to weight/cost ratio. You can
get a tremendous amount of power out of a compact universal motor but an
induction motor suitable for that would be a lot heavier and more
expensive. A universal will burn up at the drop of a hat though, a
friend of mine retrofitted his electric mower with a surplus pool pump
motor when that happened, he said it worked really well but those motors
are expensive new.