I'm not disputing that raw meat can be dangerous, but then why do people still eat steak tartare?
When it comes to beef, by and large, there's not a lot of bacteria in it that we're generally afraid of. There certainly can be for sure, but in most cases probably not. That's why you can eat rarer steaks than you can with pork and certainly chicken. Both those kinds of meat care much more dangerous forms of bacteria.
With beef most of the bacteria we're afraid of lives on the outside of the beef which is quickly killed when exposed to the high-heat of cooking. Hamburger needs to be cooked to a higher temperature because now that outside is on the inside so you need to have the inside at a higher temperature to kill everything we're worried about.
What about steak tartare which is usually made of minced or ground beef? Ideally it should be made fresh at home from a whole piece of meat using clean home chopping or grinding devices. In such a case things are more or less safe as, again, there's not really a lot of bacteria we worry about on beef so using a fresh whole cut to start minimizes the risks of food-born bacteria.
Buying ground or minced beef at the store and using it for tartare is riskier since bacteria has had a chance to grow more on the inside of the meat, there's been more exposure, and not an entirely great continuity of temperature particularly from store to home and, as said above, the sources are coming from more than one animal.
But, in the end, ground beef or whole beef portions the risks of illness, or even hospitalization/death, from bacteria is pretty rare. Beef tends to be pretty much as close to "sterile" as you can get with raw meat. Always a slim risk, naturally, but food-born illness from beef is vast less than the risks with pork (which in present day is fairly low and not as bad as it was decades ago medium-done-ness pork is fine for certified pork that wasn't feed slop) and certainly chicken which contains the most worrisome bacterias.)
