Amazon has made real money for years, they just have reinvested it. Comparing Amazon to Uber is silly, they're an established business and leader in multiple markets.
When you're running multiple new mostly-empty datacenters or fulfillment warehouses that you built for future growth, the short term efficiency (and hence income) will be pretty shitty, no? I'm not talking about the cost of building them, but the cost of running them far from capacity.