When Victa did their big push into the US market in 74 they were a run away success.
Before the end of the season the US government had deemed that swing back blades are a massive safety hazard and banned their use on domestic walk behind mowers. Fairly sure there were some USA made domestic walk behinds that used swing backs as well .
In 82 Victa exported a large number of their Vortex mowers into Canada , a fully shrouded very quiet mower again with swing back blades and the US government got the Canadian government to ban them because they were considered to be too quiet so idiot Americans would run over their own feet because they did not know the mower was running. Nothing what so ever to do with competing with local products
Now if you want to be a criminal , we do make a swing back blade mounting bracket that suites some USA mowers
And I won't say how they got there but apparently some US citizens managed to get their hands on blade carriers & blades
You might like to perouse the
RGS catelogue
Common mower sizes down here are 18" or 19" cut
The Hondas are 19" or 21"
The Big Bob is 21"
and some others are also 22"
Anything over 22" are for ride on mowers except VIC7200 which is a 24" slasher ( brush Hog to you )
And note the boss sizes as we get both US 7/8" & 1" cranks + EU 25mm cranks
And AFAIK the USA ( & Canada ) are the only countries on the planet who put bar blades on push mowers