Except they both say send. The stupid icon on the other one looks like a maraca. I would have never guessed "mic drop." Let's ignore that "mic drop" is a cultural expression that someone who grew up in a different country may not be familiar with. To be honest it look like a "send and play music" button to me.

Someday when you accidentally click the wrong button in something, perhaps when you are old or suffer from some disability, I hope that you remember this comment of yours.

Furthermore, the icon doesn't have anything for you to read, since it uses an image (whose meaning may still not be clear to an older or disabled person; it kind of looks like an ice cream cone to me).

As a person that sends dozens, sometimes hundreds of emails a day, I click the button that's I always click.

A UI that requires the user to read every button and look at every icon that they click on because it may have been changed to do something completely different is a terrible UI.

While I might notice a new color, I'm not certain that I would.

I just don't actually believe you. I haven't observed a _single user ever_ who consistently maintains the behavior you describe across all interactions they have.

In doing usability design even for astronauts or pilots I don't think you could fully trust a user to behave as you describe.