Why did the car industry stop making the on-demand 4 wheel drive that was available in the 80s on various makes and models and go to the all-time 4 wheel drive?
03 trailblazer has an auto setting that kicks in 4wd when needed, but all time 4wd does seem to be very common.
Define “On-Demand”? My 2000 Blazer has Auto-Trac which set the transfer case to 4wd, but only engages the front axles when slippage is detected at the rear wheels. This enables the truck to be driven on dry/wet pavement without binding up the drivetrain. The other settings are part time 4wd (4Hi and 4Lo), meant for part time use off pavement.
I believe Jeep and Ford both offer AWD and part time 4wd on their vehicles.
Your problem is more terminology than functionality. There were, and are, no real standards for what auto manufacturers call their 4 wheel drive systems. So, what used to be called “on demand” is now “full time” or “all wheel” depending on the manufacturer and their marketing department. What you need to look at is what a particular make and model does compared to another regardless of what they call it.
And if you think these Micky-Mouse engagement systems are trouble-free, they are NOT.
This board is full of posts that begin “I pushed the button and nothing happened”…