Erhmm some taxi drivers and lorries sort of like that also... I see no difference.

What exactly in the PSV syllabus that is actually useful?

This one I suspect they are scared kena bantai by taxi drivers

20 ft are half sized containers. We see these on the road once in a while. Standard size trailers are 40 feet long. Especially considering that joint/hitch that swivels, I'm amazed that they could maneuver it anywhere at all. I have driven those regular small lorries that only need a D + GDL. Driving them was easy. Parking was extremely difficult, even though they're so much smaller than those big trucks.. And note that you don't have a rear view mirror, because it's blocked by back of the truck.

Every other day on the road, I see inconsiderate car drivers who over take trucks and then immediately pull back to the left ahead of the truck, without leaving sufficient braking distance. Not only can't trucks stop very fast because they're heavy, if the driver stopped too suddenly, they can get killed by their own load shifting forward and into the cab, crushing the back of their head.

I am wondering if this is because Grab drivers are forever afraid of getting bad ratings from riders. If they miss the Waze indicated turn, the trip may take longer, and the rider could get unhappy because this waste their time, and result in a bad rating. If follow the waze route, there's no reason to complain.

Taxi drivers don't really care. If they miss one turn, you can complain, and nothing will happen. Not unless they take you on a 100km detour. Otherwise, you file the complain, it disappears into someone's desk never to be heard of again. Furthermore, grab rides are fixed price, but taxi rides are metered. So they lose nothing from the additional petrol and time spent getting you to your destination.