Is stopping in front of a booth, staring dead into a child's eyes for 5 seconds, not saying a word and then walking away considered "enagaging". Because at that point saying no thanks isn't that much more effort.
No its not considered engaging IMO, because it happens reflexively, unlike verbal communication. I often look at people who talk to me from the side (usually trying to sell something) because it takes me a sec to realize what they want. Lost in thought and such.
So I can absolutely see the scenario where I (in theory) look at someone trying to sell me stuff and keep walking once I decide I'm not interested.
Admittedly only been in a remotely similar situation when kids tried to "sell" magazines to me at uni though, which was just a front for aggressive begging. Honestly can't say if I would've taken the second to answer your kids in that hypothetical, 100% used to not answering people selling stuff, but then again they are small kids doing something (I guess) non-suspect, so idk