Until your employer or government requires a side-loaded app for you to do something that you need to do.
If you don't want to buy on Walmart and their custom payment system, then just go to a competitor.
With that said: this is an unrealistic scenario. Walmart doesn't pay the famous 30% to ApplePay, only a regular CC-like fee (probably less). Also, physically they can just accept contact payments where they don't interact with Apple but it still works with the iPhone wallet. Online, they can just use credit cards instead of ApplePay, which iPhones have autofill for, and probably not lose much.
There’s also situations where you don’t have a choice. In many parts of the US the only reasonably accessible store (and sometimes grocery store) is a Walmart.
There is a real solution to this, where we codify our social limits through legislation and open standards to prevent these horrible "leopards ate my face" scenarios that everyone seems to hate so much. Or we could keep trusting Apple, and see how many F1 advertisements that nets us in the long-run.
The ones that get into office are most often out of touch and in someone’s pocket because they grandstand on polarizing topics that information-deficient and single-issue voters flock to. I try to vote for candidates who I think will do good that way, and it makes some impact on the micro scale, but on the national scale it’s like trying to drain the Pacific Ocean with a thimble.
Are you now going to argue that Tim Cook is a really nice guy who practices genuinely principled leadership? I hope not, he's only there to convert your loyalty to something more liquid and fungible.