Toddler Safety

I have a quick question for all the mommas out there. My son is almost 18 months old and very hyper, when we go out in public and I let him walk around he has a tendency to run off. Of course I stay near him, but I think that it would be easier and a lot safer to use one of those backpack harnesses in public places. He's very friendly and loves to say hi to other people and chase after other kids to play.

I've seen other parents get their kids to follow them by saying "bye bye mom is leaving" and then slowly walking away and of course the kid starts crying and chases after them. But if I do that, he bursts out laughing and continues to run wherever he wants to go.

I spoke to my mom about it and she says that the harness is cruel and that he needs freedom. However, in this day and age, with freedom can come consequences, I'd rather know my son is safe.

Would you use a harness like this in public places?

TIA!