If you have used their app and done a review of their platform comparing it with Uber, can you please share.
Indeed Uber did try to enter Indonesia they failed, they were out of most of South East and East Asia, because they don't have enough engineering talent to build a system for those specific countries, local companies like Grab in Singapore, Gojek in Indonesia, Didi in China beat them. So why would you think those companies do not have a talent to build systems better suited to their own environment than Uber.
Because they don't understand the local market, period. Nothing more than that. It has zero relationship with Uber not able to hire engineering talent. They simply don't know the market.
If you put the smartest engineers in the room but they don't know the business domain, they will fail from Day-1. I think people put Engineers over everything else where in majority of the situations, business-domain-knowledge trumps engineering excellence.
That is one reason. The other reason is that Local will choose Local (China with tons of Chinese only service). Indonesian President, Mr. Joko Widodo, for sure will promote Gojek more than Uber.
> So why would you think those companies do not have a talent to build systems better suited to their own environment
You have to understand the context here.
Why do you think Gojek opened a huge "lab" in India?
Why do you think Grab opened a "lab" in Seattle and hired Steve Yegge?
You may not realized this but they are not the only South East Asia "Unicorn"/"Decacorn" who opened R&D Labs outside their "homebase".
I can't share much of the details why these companies (_and_ a few others) decided to do so but feel free to guess a bit here and there.
Uber couldn't iterate the platform and technology according to local market requirements and conditions, engineering is one of the reason for failure. They then tried with money and didn't work either. It's a combination of business and technology platform due to which Uber failed.
If you prefer to live in a bubble its fine, there is no better engineering talent anywhere in this world except Uber. But ground truths are already there in the markets from which they retreated.
Gojek opened centers in India because it's cheaper than Singapore.
Grab costs in Singapore and Malaysia is higher too compared to India.
So like any other USA firm which has opened centre in India to save costs, they did too.
Grab isn't the only one from SE Asia that opened the lab in North America. There are at least 2 more from Indonesia that opted North America instead of Singapore/Malaysia/India.
Can't share details other than "talent pools just not there".
Feel free to disagree with the execs.
Sure they will open in Seattle as it's 30% or more cheaper than Singapore. Grab's largest R&D team is in Singapore. They did bring in talent from around the world here. But as the cost in Singapore is very high, to get an expat is very expensive. 
So it does make sense to open in cheaper location an R&D, it also shows they have engineering talent from around the globe.
Google Fresh Grad total compensation should be between 150k - 300k usd in Mountain View. Fresh grad. Seattle usually cost 10-15% less total compensation compare to Mountain View.
Heck even recent Microsoft offer for fresh grad base:110k, bonus 10-20%, and rsu. That's MSFT, not FAANG. FAANG will give you signon bonus on top of that ranging from 50k-100k.
Keep in mind Grab RSU is paper money at the moment.
I highly doubt Singapore engineers, given the same level, make that much. Probably only the top 0.5%.
I don't see a good discussion as you still think that these folks don't come to North America and open R&D lab because it's cheaper than Singapore since that logic does not make any sense out of the gate: India is way cheaper, why not grow there and don't even bother opening a lab in Seattle. You do know that it is damn hard to grow an R&D Lab in the USA due to regulations and immigration policies right.
In order to avoid repeating the facts on the field, I would suggest you to reach out to the executives in those companies and ask why they do so as I have done before to avoid confusion, assumptions, and guessing games.