Sixteen dollar kids meal

My 9-year-old son was hankering after a fast food kids' meal. I was busy, and in a good mood, and it had been awhile since he'd eaten out. So I gave him five dollars and sent him pedaling away on his bike. (Lest you panic at my mothering, the fast food place is only four blocks from home, this was right after school, and we live in a small town.)
When my boy came home, he had no kids' meal, but a sack with a dollar hamburger in it. "Where's your kids' meal?" I asked.
"They said it was sixteen dollars," he said, his face sad. "They had really cool, toys, too, and I wanted one."
"Who told you it was sixteen dollars?" I asked.
"The worker," my son answered. "When he told me sixteen dollars, I asked, 'Are you sure?' and he said, 'Yes. Sixteen dollars.' So I got something from the dollar menu instead."
I was an unhappy mother. It put me in mind of the time I parked my recumbent bike outside a convenience store/gas station in town and let this same son out of the bike trailer to go in and buy four ice cream sandwiches for a dollar. There was only one sandwich in the freezer, and the clerk said it would cost him forty nine cents. When my son came out to tell me, I stalked inside and talked to the clerk, who, lo and behold, went in the back to open another box of ice cream sandwiches and only charged me twenty five cents each.
WHY COULDN'T HE HAVE DONE THAT FOR MY SON? Why pick on kids just because they're short?
I didn't get to the kids' meal food joint that day, but a couple of days later I was at the counter, asking for a toy that my son would surely have gotten if he hadn't been misinformed. The manager ended up giving me three toys.
That was soooo nice of him.
Other people just need to grow up.