let me tell u that u have every right not to allow ur child to walk away with strangers or even get out of ur sight. i'm from egypt, and there it's pretty common for strangers to offer children candy as an act of kindness. some ppl would even be offended, if u refuse to take it from them. (i personally wouldn't want my child to eat sthg that i don't know)
but taking a child out of his parents sight is completely different. come with my i'll give u candy is like u said, the typical thing a kidnapper would do. growing up, we were warned from walking away with ppl we don't know. and that's exactelly the type of things we were warned against, i'll give u candy, i'll take u to ur mum,...etc
yet some parents, maybe out of ignorance, or out of good intentions still allow their children to walk away with ppl they barely know. they believe, if it's just for a minute or sthg, it's okay. that's way child abduction is not unheard of in egypt, and i believe in many arab countries.
u should never let ur child out of ur sight. i don't even allow ppl i don't know to carry my child (he's only 3 months old). a lot of times, in public bathrooms for example, ppl offer to carry my son until i go to the bathroom. or sometimes waitresses in restaurants want to carry him. i politely say, he would cry if someone he doesn't know carries him. i believe that more 90 per cent of the time, ppl rn't planning on running away with him. but i would put my child at such a risk. and i believe no one should risk sthg like that.