Was the thatch placed before the sides?

Hello Rabbi,
I wanted to ask about a person who eats in a sukkah and does not know who put it up, and it is not easy to find out, should he be concerned that the thatch was placed before the walls and is invalid on the grounds of “made and not from what is made”?
For example, eating in the sukkah of a bakery or restaurant, should I be concerned about this? And suppose I asked, is the person being questioned considered faithful if he does not observe Torah and mitzvot?
I was inspired to speak after, during a visit to an IDF base (Arad Camp – Home Front Command) a few days before the holiday, I saw a sukkah near the dining room in the middle of being built, with the thatch already laid and tied, while the walls had not been erected at all.