Your surgeon:

"He's new to this! He didn't understand protocol and that you were supposed to use sterilized equipment and wash the previous patient's blood off before he took the scalpel to you! So what if he cut off the wrong limb and gave you a tainted blood transfusion! He's learning on the job!"

Your banker:

"He's new to this! He didn't understand protocol and that he WASN'T supposed to be making unauthorized transfers of your money into high-risk investments. So what if he forgot to send in your trade requests and made various calculation errors. He's learning on the job!"

Your mechanic:

"He's new to this! He didn't understand protocol and that you're not supposed sit in the car seat when covered in oil! And sure, he destroyed your engine and transmission and scratched every inch of your vintage car's exterior, but he didn't mean to! He's learning on the job!"

Would these situations fly with ANYONE? Why is it acceptable for the PRESIDENT OF THE UNITED STATES to be a total dunce who is unaware of basic duties and protocol and is just "learning on the job"?