Buyer not including last name

Recently I have had several buyers not include their last name on the order. I then have to email asking for it. One I never got a reply so I canceled the order. A few others replied, but one didn’t respond for days (three attempts) and resulted in a late shipment ding. I emailed seller support about it asking them to change my rating, but haven’t heard back yet.

Now once again I have another order where the person didn’t include their last name. I have emailed twice, no response. Should I just cancel? What is up with this trend? Since when did people stop putting their last names on orders? I noticed on amazon there’s only one field for name unlike most online stores that have fields for first and last names. Amazon just says both are required but only has one field. Including both should just be common sense.

I am in the US and the customers in question have lived all over the US so there’s no geographic trend.