cessnapaul

The majority of credit/debit card purchases are now Card Not Present (CNP) transactions and growing, it was 32% of all transactions in 2020 according to the Fed. Card present actually declined by 7%. ApplePay is considered card present by the issuers btw.
The banks have massive fraud detection programs and algorithms to protect consumers and themselves from fraudsters. And as pointed out above, Apple pay operates with the EMV standard.
While ApplePay does have have security embedded within it, Apple does not hold some kind of monopoly of credit card security.  

Apple have been successful and created a new market place in 2008 and is warranted with all that success, to the point that  is doesn't abuse it. 
This is now about app developers ability to negotiate with apple over that value they bring versus the mandated fee Apple takes.
In your Walart example, a typical supplier works with Walmart over the sell price, shelf location, Walmart's margin, promotion times, end caps, marking support, discounts etc.
No App supplier is able to do this with apple. It's a take it or leave it scenario. 

There needs to be a balance between the consumers right to buy an apple phone, the consumers right to purchase any app they want on that said phone, the price that the App developer would like to offer that App at (and in-turn the consumers propensity to pay that price), versus Apple's 30% markup.
Developers should be able to negotiate, this is what this is about.