As someone in culinary school, I understand how it can be completely frustrating for a chef to cook meat well-done, especially at a finer restaurant. They are usually buying the best prime cuts of meat with beautiful marbling, and especially with cuts like tenderloin, they are often losing money because the food cost is much higher.

The fact of the matter is, the longer you cook a piece of meat, the more the proteins coagulate and the more "juice" (actually that beautiful marbled fat is what makes a steak juicy) cooks out of the meat. This does make the meat tougher. I recommend checking out any of Harold McGee's books for anyone who wants to understand the science behind it.

So my point is, from a chef's perspective, when they cook a steak well-done, they aren't cooking it the way to best showcase that ingredient. And like, PudgieBelly said, they often find it an insult to their talent. Chefs often see themselves as artists, and most people don't realize how much time goes into the creation of a single dish.

BUT, as much as it may irritate a chef, a good chef still realizes he's in the hospitality industry and the best way to make money is to accommodate your customer. A good chef will have no problem making any sort of concession for a customer, no matter how much they may disagree.