When new homes are built, plumbers are asked to bid for the job.
Most bids will say something like "competitive" toilet, lav, whatever. That means we get to pick something to fill the hole so that the builder can sell the home.
A competitive toilet is whatever we chose to install, and most of the time, it's whatever we're getting a good price on from the wholesaler.
When I started putting my report on toilets together, I was getting many comments from the plumbers I was polling that read
"I've been installing "well known brand" for thirty years, and nothing works well."
Do you think the plumbers really care?
They don't. It's about putting food on the table.
A successful home builder may be working on a 5% profit margin. Do you think that is going to be jeopardized by "upgrading" components in the home? When a home is sold, the buyer sees a white porcelain throne. Good enough.
I built and sold homes for a while. And I've plumbed plenty of homes in my day for other builders. That's how it works.
That being said, at least the 3.5 toilet worked well enough.
The first 1.6 toilets were pretty bad.
Currently, you can buy a good 1.6 that will outperform the 3.5's
There is less plunging with a good 1.6 then there is with the old 3.5's
3.5's became extinct after 1991
That's twenty years ago.