You know, some very low cost small lightweight minibus or small pick up ( these are under 1,400KG body weight empty vehicle ) in my country long time ago are all drum brakes. No ABS for sure.
I can't module those brakes well for its maximum bite , as I am so used to vehicle with at least front brake must be caliper type.

Some of these 4 wheel drum brakes are dangerous , often I see their rear brakes locked first and vehicle almost goes to weird tail spin at a mere 40 MPH.
Must be the servo effect.

 

Been doing the same with disk brakes on no ABS cars as well.
You are mixing different things.

 

This is an adjustment issue or equipment problem and lack of experience or know how with operator. Drum brakes non abs requires the operator to be in control of the brakes. Think manually pulsing as necessary. Pretty typical of drum brakes just fyi.

One safety issue I ran into with 60s vehicles were going thru large puddles if the brakes got wet the ability to grab was near zero, made for fun times lol.

 

Well, I should explain further, as automotive development are different around the world.
There are vehicles in my country ( Indonesia ) which are POOR country specific, they are not sold in any other 1st world countries as the safety standard will never be met. I am speaking of early 1980.

This is the model I speak of, don't laugh

Introduced in 1977







Early 80 they made it to minibus version as cheap local transport.




These are the specs :



Today, 1 US$ = Rp14,800
In the 80s, US cars were so cheap, unlike prices in my country. So if this Toyota cost US$3,132 in 1977, it was the component import tax + all rip off of a typical 3rd world country.


Yes, I lack practice on such low cost un-safe vehicle braking system. That is a fact.
I was in Singapore from mid 70s to mid 80s and I only get the chance to drive this un-safe Toyota when I came back to Jakarta-Indonesia during holiday.

However, I do enjoy learning/driving this low cost vehicle and experience how awful its braking system is and how poor its handling is.
One of the thing I like to test is the brake, yes no ABS yet on any cars I driven back then, not even on my family's 280SE W126 of the 80s model or my own modded daily MK2 Toyota Supra of 1983.
If ABS can do 99% braking without locking, and say my own skill on caliper based brake can do 92-95% without wheel lock up , I would equate the drum brakes on this un-safe Toyota as 80% at best and pushed harder I get wheel locked up.
If a disc brake is much easier to modulate its last 10% before lock up, a drum brake would need 20% range before lock up, and I am certain the servo effect has much to do with this.

I am speaking of pushing the brake limit driving style and not casual driving kind of braking.

 

Well... some of those cheap cars make it to America
My 1st own car in Poland was Fiat 126, so that video brings some memories.