I thought that since most are independent sales agents and receive commissions, they are more customer-oriented, at least when they can assume that someone really wants to buy from them.
You still have a lot to learn. After all, you have correctly understood that most in-house salespeople are independent sales agents. However, they are not customer-oriented, but commission-oriented. That would only align if they were paid for your satisfaction – but their commission basis does not increase with your happiness, but with the purchase price. With the last sentence, however, you are more right than you might realize: they mainly want you to buy before they switch to the next company and their successor would reap that you buy. By the way, you should almost certainly assume that after half a dozen model home visits and a month of reading in this forum, you will know better than the salesperson (who was often in a completely different industry before). If you have understood anything very well about construction topics—how it works or what differentiates it from something similar—then have some fun and let these guys explain it to you.