why do bakers get 13 in a dozen but the rest of us settle for 12?..

The next time you get the gift of an extra doughnut added to your dozen, thank crooked 13th-century bakers for the bonus treat. In the 1260s, British bread makers were notorious for shorting customers with skimpy loaves. King Henry III was so irked by the problem that he implemented a new law to standardize the weight of a loaf—selling puny loaves could result in beatings or jail time. Since bakers wanted to stay on the right side of the law, one common trick was to give 13 loaves to any customer buying a dozen. Even if the loaves were light, the extra would cover the shortfall. It was an easy fix for bakers, and since low-carb diets were still seven centuries away, customers rejoiced.

They need to get rid of the ones they dropped on the floor somehow.

According to Google it's believed that bakers would toss in an extra loaf of bread when selling a dozen to avoid being penalized for selling short weight.

One is for the baker

the baker's dozen is what bakers did to ensure the did not accidentally cheat customers costing them their bread selling licenses this date back to the Roman empire

probably one is to cater for the egg which breaks into a chick..lol

One's to eat on the way home...🍩

Baker needs to eat too.