> They certainly have the power to

They tried that with WalmartPay. After about a decade, they gave up[1].

Consumers have a lot of agency. A lot of people get paid access to one of the other platforms by virtue of tie-ins with their mobile carrier, or bank, or whatever. There's low incentive to pay again to use Walmart's delivery service, which will not also bring delicious Thai food for lunch.

1 - https://techcrunch.com/2026/08/21/walmart-to-finally-start-a...