That's a fair point, a test in an environment where social norms force conformance to rules is less helpful than such a test where there is no/little social enforcement against bad behaviour. The same time though, when you are in a dating environment, then you know that the other partner is also judging you. So sure there are people who leave on the first date and stuff like that, but people will always present some version of themselves towards people, whether you are a stranger or a friend. But lying to a friend circle for a long time is much harder than lying on someone you only met through some internet chat app with pictures

For example, it's easy for a cheater to not tell on apps that they are in a relationship, while it's tough to lie to an entire friend circle about that. They would have had to join the friend circle just with the plan to mislead people. I'm not saying it's impossible, just that it's a higher bar. Like leaving an unlocked bycicle around vs one that can be opened in 10 seconds with a 50$ tool: with the first you can drive off immediately upon discovery while the second requires you to bring the tool with you.