I'm sure we've all acted the same somehow.
At the LATCH meet up we had last Friday, one of the moms had her son with her. The son was asking for this and that, even orders that were not technically theirs. All the other Moms were prety generous, assuring his Mom that it's ok while his mommy said, "No son, you cannot have everything you want."
We kidded her about how most parents are like, "I want to be able to give my kids the best, everything that they want, that they should never want at all." But the truth of the matter is, we are always more strict about and with our own kids. After all, disciplining other people's kids isn't our business nor our concern.
Hopefully though, i'd still manage to be more empathetic with my own kids :)