There’s no way to say this without coming across as extremely rude, but…
> I give my kids business cards with my phone number to pass out to their friends to give to their parents
If this isn’t the only thing you/your kids do that’s well outside typical social norms, that’s probably the reason nobody else is inviting them. This is almost on the level of parents accompanying their adult kids to job interviews and then wondering why their kid didn’t get an offer.