Presumably those other businesses are able to generate more revenue per employee. Otherwise, they'd go out of business (which happens all the time), as Uber and Lyft are doing here. What do you believe their profit margins are? Uber's latest investor update says theirs was ~2.9% last year, though that number probably requires a decent amount of familiarity with the business to interpret.

I can't imagine investors would be very happy about them choosing to posture instead of making money with their investment if that's what they were doing.

Obviously investors want better margins. Treasuries are paying 4-5% guaranteed, so why invest in Uber to make 3%?