The only reason things are legal or illegal, allowed or disallowed, is because the majority of the voting public deems it to be so. There is no possible set of rules that can reflect every individuals sense of right and wrong, since we disagree strongly and in good faith about those matters.
Building codes exist because people died in fires. Limits on working age exists because there would be child labor without it. Limits on working agreements exist because there would be indentured servitude without it. Limits on government power, exemplified by the first 10 amendments to the US constitution, exist because without them the government would do anything to you that it wanted. And even then there are those who find those regulations limited, who want government with unlimited power over them, thinking that would make them safer, or that it's coercive to government workers to abide by them. Society is not a game of absolutes - it's a game of compromises that can only function if people are generally acting in good faith.
I think you've strayed from the herd a bit too far here. We're talking about a retail establishment accepting cash payments or not.
You're trying to make moral comments on labor laws or something. I'm not really sure the point. Regulations to run a business can be deemed as protecting what's "right". While we can commonly agree that it's "right" to provide accessibility access to your establishment, we can hopefully also agree that if it wasn't legislated to be, then more than a few retailers would not provide them.
However, none of this has anything to do with a retailer's decision to accept cash and all of the risks associated with that.
Building codes exist because people died in fires. Limits on working age exists because there would be child labor without it. Limits on working agreements exist because there would be indentured servitude without it. Limits on government power, exemplified by the first 10 amendments to the US constitution, exist because without them the government would do anything to you that it wanted. And even then there are those who find those regulations limited, who want government with unlimited power over them, thinking that would make them safer, or that it's coercive to government workers to abide by them. Society is not a game of absolutes - it's a game of compromises that can only function if people are generally acting in good faith.