I obviously can’t speak for drivers but I have spoken to 2 who both said they preferred grab over Uber because they picked up many more customers.

I never used Uber because it was never cheaper than booking a taxi over the phone.

Grab did a lot more than Uber for their app too. Pretty much from day 1 you could type a taxi stand number in and it would pin the exact location. Uber couldn’t even come close to figuring out where I was standing. So personal booking and usage experience was far better than Uber for sure.