newer mowers have been regulated by the feds, design of discharge hole,
limit blade tip speed etc.

now all these make mowers safer but can adversely effect mower
operation.

heck new mowers have carb adjustements permanetely plugged so you cant
easily raiue engine speed.

this is why really old mowers were 2 or 3 horsepower and newer ones 5
or 6 hp and often dont work as well as old ones.

our federal governmment at work......