Why is it safe for steak to be pink in the middle but potentially dangerous for a hamburger not to be cooked all the way through?

Chef's answer
It is safe for steak to be pink in the middle, but potentially dangerous for a hamburger because pink in the burger means that it is not cooked all the way through. ... During the cooking process of the steak the bacteria on the outside of the steak will be killed off making it okay to eat the pink part of the meat..
Frequently asked Questions 🎓
If you'd like your steak medium-rare, it should feel like your cheek: tender and soft but still fleshy (as opposed to raw, which would be just soft). If you want a medium steak, touch your chin: The steak should still be tender, but with some resistance.
The best way to defrost steak in a hurry Simply fill a large bowl with cold water, place your steak in a resealable and leak-proof plastic bag, and submerge it in the water. If your steak has been frozen individually in a vacuum-sealed bag, it's okay to leave the steak in the bag when you submerge it..
A spoiled steak will have a potent odor that no longer smells like raw steak but instead has an ammonia-clad aroma. You'll definitely know the odor when you smell it, and it's a sure-fire sign that you should not plan to eat it! It's important to note that your nose may not also be the best thing to use..
It is not uncommon to pair a white wine with the seafood to start, then progress to a bolder red when you make your way to the steak. We recommend a full-bodied wine to start, such as a California Chardonnay, followed by a red rich in structure, such as a Bordeaux.
Depending on the thickness of the cut, you should leave your steak to thaw in the fridge for at least 12 hours. Most pieces of meat will need 18-24 hours to thaw properly, and a particularly thick cut could require up to 30 hours..
Freezing meat keeps bacteria in a dormant stage. However, once thawed, these bacteria can become active again. Never thaw meat on the counter or let it sit out of the refrigerator for more than two hours..
Spotted on CTi News, a Taiwanese cable TV network (via Women's Health Mag), the idea is pretty simple. Turn one of the pots upside down and place the meat in a bag on top. Next, fill the other pot with room temperature water and put it on top of the steak.
A few more cooking questions 📍