I saw two similar situation in a hobby store in Italy years ago. A kid (probably 10) that wanted to buy a model kit, because on the box art it looks cool, and the guy on the store almost sold it, but when he ask a the kid if he needed glue/paint, the kid realized that was not a Lego, and you need glue/paint to build. So he left the kit and the store.
The second time, a couple (mom/dad) were looking to buy two kits for theirs kids as Christmas gift. They were looking to buy some Tank model kit, ant they were saying "so they can build them and play" the guy a the store was supporting the idea too. I didn't. I ask them how old the kid where, and show them on the box that they were under the suggested age. Plus I told them that for build them you need glue, and maybe paint, because it doesn't look like the box art, and the piece need to be cut etc... I was buying a kit to, so I open the box and showed them how it was. A the end they tanked me for the help, they would have buy something wrong. The guy a the store was not very happy with me, I understand that he want $$$, but...
Glad you find the post Jean-Jacques! Thank you!