What is with those people who don't want to let kids touch anything?

When my fun loving wildly sweet little boy, takes to the world, people we meet or pass are usually amused and joyed by his innocently mischievous behavior.  I rarely prevent him from interacting with others, or apologize for his actions.  I have seen mothers that keep their kids arms length from others at all times, and will snatch their kid up if he comes over to examine what you are doing or playing with or dares to ask a question or ask to touch something.  I am of the mindset that he is a kid and that means he is going to ask questions and want to play with things, observe and discover.  Most of he time people are delighted by his cute phrases and endless energy.  

But then there are some people... "don't touch that" "you can't climb on that"  "those are not for playing"  "no no no."  I think those people have big sticks up their butts.

Like today, we went to Trader Joe's after I got off work to grab some groceries.  Both LittleMan and GirlFriend were sitting in the cart as we shopped.  I gave them each a banana to eat as we wheeled though the store.  When we got to the check out counter the kids helped hand the groceries to the cashier to ring up.  LM was too close to the giant captain's bell that the cashiers ring when they are short staffed - that was my bad - I was grabbing groceries out of the cart and did not notice that he could not resist the temptation and rang the bell!  Ding - dong - ding - dong, "I'm ringing the bell mommy."  That made his day but made the cashier cross.  "No you can't do that" he said with a very angry face.  I took LM out of the cart and started to explain to him what the bell was for as I paid for the groceries.  As I was using the electronic pen pad to pay with a credit card, LM asked, "Can I?  Can I"  and reached for the pen.  After I finished paying, I let LM take the pen to pretend to pay too - but the cashier snatched it out of his hand, "No." I don't think that it would have done any harm, the pen pad was frozen until someone swipes a card.   He gave a very ticked off face on top of the contemptuous glare that he gave when I asked to throw away the spent banana peels.    

But maybe I'm missing something dangerous.  Maybe I'm way too lenient with my kids and I should keep them on tighter leashes.  I just don't take life seriously enough for that.  Not that I never enforce rules, just that I try to only make rules when there danger of harm or hurting someone.  I don't like to let social norms get in the way of exploration.  And I like that out-of-the ordinary behavior makes old people talk to you - breeds  precious human interaction from strangers, and creates a break from the mostly mundane routine that lots of people with 9-5's face.  Those rotten party poopers can just deal.