I get that, but for these pop-up shops selling to partygoers out of large tanks it seems like very little extra effort and expense for a dramatically improved user experience. Market forces alone should be enough to incentivize adding oxygen.
Next you're going to expect them to use gases that are sourced for human consumption. But this is a gray market. Nitrous isn't meant to be used this way; so a gas supplier won't want to sell the healthier alternative for fear of getting caught knowingly selling it as a drug.
