You are right about lock-in, but there is a significant convenience factor. I mean network effects as in eBay (more buyers, therefore more sellers, GOTO 10), no

You are right about lock-in, but there is a significant convenience factor. I mean network effects as in eBay (more buyers, therefore more sellers, GOTO 10), not like Facebook (i.e friends). If Uber has the largest fleet it really makes it hard for other services to compete as no one wants to check multiple apps for that (and the existence of aggregators a la Kayak needs some sort of open API, which I don't think exists).