Sometimes it is the tech... just not in obvious ways. You have to look beyond the basic spec.

Uber and Lyft are not just taxi apps. They are massively polished. When I use them I am astounded at how good they've gotten the UX and then I shudder at how hard that must have been across two mobile platforms and in the presence of very unreliable networks. I've ordered an Uber with no cell Internet using barely usable coffee shop wifi from a block away.

Then you have scaling, which brings up or creates issues you just do not see at smaller scales. Big O type considerations and weird edge cases that only come up once every billion transactions start mattering.

Then there is all the big data stuff. These services do tons of route optimization and analytics.

So yeah marketing, sales, fund raising, management, etc. also matter but tech often matters as much or more. It's just that junior engineers usually only see the tops of icebergs. This is why despite decades of pure biz people saying "tech doesn't matter" you still rarely see founding teams succeed without at least some tech founders but you do occasionally see even lone tech founders make it. (But those tech founders do have to know or be willing to learn the non tech stuff!)