Kids learning that adults systematically lie to them is probably beneficial and adaptive (which I suspect is why humans feel compelled to lie to kids).
I'd prefer for adults to adapt to not systematically lying to kids, if it's not so much of a disruptive inconvenience to your lifestyle, thank you.
Speak for yourself, if you believe the benefits of lying to your own kids outweigh the benefits of raising children honesty. You can have an honest discussion with your children about how OTHER people will lie to them, without having to lie to them yourself to prove it. It's not something that's hard so hard to prove that you have to betray their trust by doing it yourself. Because if they don't trust you enough to take what you tell them at face value, they already know you're a liar.
I believe the main reason some humans feel compelled to lie to kids is simply because they're compulsive liars.
