Frankly, the R&D spend is the least of their worries. They recently trimmed some fat from their marketing department but the subsidized rides problem continues to be the biggest issue they face financially.
Try hailing a cab in Thailand, Indonesia or Malaysia. They will ask your destination and quote you 5-10x meter fare. Use a ride hailing app and you get approximately the meter fare.
Uber is not a tech company. It’s a taxi-company with a fancy app.
There’s literally no reason their operating expenses should be this big.