Not all NEW customers processed via the POS are treated equally. I have identified an inconsistency that has to do with flagging customers as "Accepts Marketing" and "Does Not Accept Marketing." It is easy to identify and reproduce in any shopify store.
When a NEW customer checks out via POS, pays cash, and leaves an e-mail for their receipt, a customer account is created for them that's flagged "Accepts Marketing."
When a NEW customer checks out via POS, pays credit, and leaves an e-mail for their receipt, a customer account is created for them that's flagged "Does Not Accepts Marketing."
Seems simple enough? Well according to shopify support "it's all in my head." In multiple support emails they have tried to convince me that I am deliberately checking out customers differently, and that I'm creating these customer accounts and choosing which to flag for marketing. (Then apparently after purposefully flagging customers differently, I am complaining to support about the difference, making some wild claim about an "inconsistency on their end".) However that's not the case at all. I can reproduce this inconsistency every single time checking out customers exactly as stated above. The kicker here, based on their responses, shopify support hasn't even attempted to process customers as I have mentioned, because if they had I know they'd get the same results.
So WTF shopify? Identifying inconsistencies such as this, is wonderful information to have. It allows you to refine your platform further. But instead of listening to your clients you've opted to scoff this off as "user error" without even an attempting to determine if maybe just maybe there's actually an issue.
First, thanks for bringing this issue up. Sounds like our support team mistakenly was working with just the iPad version of POS. We've been able to reproduce the issue here with the steps you provided—which were very helpful, thanks for being so clear.
We'll be fixing this to respect your shop's default customer marketing preference regardless of payment type used. This will be part of our next update to Shopify POS.