The push mower market is very price sensitive so it is a case of cheapness outsells quality 5000 to 1
Quality costs money and if the mower is making you money then quality , longevity & ease of maintenance are a lot more important than the price tag.
So commercial mowers have better engines than domestic mowers .
B & S has been in take out profits mode for decades & done next to nothing in the way of upgrading their engines .
So as they get squeezed on price the quality goes down.
They have also been designed to use the cheapest available parts, thus the smallest number of the screws that will do the job .
They have not realized that times have changed, slave labour is no longer available so reduced number of different fasteners & making engines easier to assemble is the route to profits.
Loncin engines are made in a new factory designed off the GCV Honda engine , slightly reworked so it can be 100% machine assembled thus it will be a lot cheaper than a B &S to start with and that is before the artifically low exchange rate makes them almost a give away price .
As a long time mower mechanic friend used to say
There was nothing wrong with a 1950 B & S engine so there is nothing wrong with the current one as the only change is plastic has replaced the steel & plastic does not rust .
I for one have stopped using B & S engines and only fit Kawakasi , Loncin or Ducar engines now days
Kawakasi if the customer has a good quality mower that has a lot of life left in it , Chinese engine is the mower is not far from the scrap metal bin.
The only reason to fit B & S in the past was parts availability and now that B & S Aust can not be bothered to bring in parts I am not going to import them to keep my customers mowers running .