You haven’t looked hard enough. This is the kind used by health inspectors, chefs, and TV hosts (well, at least Alton Brown uses one). Mine works great. They’re a little pricey, but they consistently give super-fast, accurate readings. This ain’t your grandma’s craptastic dial meat thermometer.
I second the Thermapen. I’ve had one for years, and it is always spot-on. Wouldn’t grill without it.
I’m starting to get probe-envy from their new splashproof model though… Despite the fact that I’ve splashed mine on several occasions and never had any issues (yet).
The answer to both of these is that the average, untrained person really doesn’t know precisely what terms like “medium rare” or “medium” mean. For professional cooks/chefs, these terms have specific definitions, and those definitions are based on temperature, not look and feel. (Though once you’ve cooked a few thousand steaks, you get a pretty good idea of how “medium rare” etc. should look and feel.) The untrained person tends to base the definitions on how Mom (or some other non-professional cook) did it, and Mom in turn learned it from Grandma, who may have learned it from a cookbook that showed pictures of what different degrees of “doneness” should look like. And who knows how well the color was reproduced in that cookbook, or how faded the pictures became over time.
Our local health department stresses the fact that you can’t tell if meat is “done” by just looking at it. This is especially important when cooking things like poultry. The chicken breast might look like it’s done, but if it’s not up to the proper temperature then it’s not safe to serve.
If a piece of beef is cooked to the degree you like but the thermometer says it’s not there yet, that’s fine, but it doesn’t mean the thermometer is wrong. It just means that it turns out you like your beef a bit more rare than you thought you did.
On a similar note, in my years as a breakfast cook I saw the same thing with eggs. I can’t count the number of people who ordered “over easy” eggs when what they really wanted was “over medium”. This was made obvious by the number of people who ordered “over easy” and then sent them back because the whites weren’t cooked all the way. Well, sorry, runny whites are part of the definition of “over easy”. What your mom called “over easy” is irrelevant.
As others have already pointed out, yes, yes we do. Except for the running part. Never run in the kitchen, especially when holding a sharp object 
Heat always radiates toward a cooler area. So if the outer part of the roast is hotter than the inner part, the heat will continue to move from the hotter part to the cooler part, and the temperature of the inner part will rise accordingly until equilibrium is reached.