There are different “factions” and accreditation organizations in Montessori. Some are more liberal and others are authoritarian and rigid. Not all Montessori schools are like you describe, but some certainly are.
In our market we see lots of the use of the word Montessori for marketing value only, when it practice it often means something like: "we have a bunch of wooden toys and a certain aesthetic in our classroom." I've heard these referred to as "Monte-sorta."
I agree, and sadly this kind of gives the Montessori label pretty limited predictive value. Turns out you just need to find a good school, regardless of label.
It really comes down to the teachers skill and personality- and that often comes down to if the school can afford the best teachers. Often in the USA regular public schools in wealthy communities will have better teachers than you will find at most private Montessori schools.
Part of schools "affording" the best teachers is not money, but the amount of discipline problems they need to deal with. Which correlates to the financial status of the families at that school. For tons of reasons.
Which families tend to win the lottery to go to these schools? The parents that can afford to. Even if the school is free, the transportation is often not. Plus the parents have to have enough free time to be aware of the lottery for their 3 year old.
most improper ones are simply capitalizing on the name recognition, some may have the idealism but fail in the implementation. if you do enough research it is pretty clear that only AMI accredited teachers implement the original method as designed by maria montessori. AMS comes close. and everyone else never received any form of montessori training at all.