If Wikipedia is to be trusted (and in this case, their source is the FDA), there is in fact a toxin in some raw beans, such as kidney beans.
The toxic compound phytohaemagglutinin, a lectin, is present in many
common bean varieties, but is especially concentrated in red kidney
beans. White kidney beans contain about a third as much toxin as the
red variety; broad beans (Vicia faba) contain 5 to 10% as much as red
kidney beans.3
Phytohaemagglutinin can be deactivated by boiling beans for ten
minutes; the ten minutes at boiling point (100 °C (212 °F)) are
sufficient to degrade the toxin, but not to cook the beans. For dry
beans, the U.S. Food and Drug Administration (FDA) also recommends an
initial soak of at least 5 hours in water, which should then be
discarded.3
During the pressure-canning process beans undergo (they are fully cooked in the can), the toxin is certainly deactivated. Canned beans are ready to eat, even cold, although they probably taste better hot, and with some flavor from a sauce or accompanying dish.
The danger would be in slow-cooking dry beans of this variety, which have never been previously cooked.
Braises are, by their very natures, cooked to well done. They achieve an internal temperature well above 165 F which will make every meat well done.
Please see:
Why would a pressure cooker shorten a braise time?
for a detailed discussion on how the collagen to gelatin conversion takes place over time, and is made faster in pressure cookers.
The fact that the cuts that are suitable for braising are exactly the ones that allow the slow conversion of collagen to gelatin is what makes the pressure cooker suitable.
The real issue with cooking braises low and slow in the conventional oven is that at sea level, the internal temperature cannot get very high, so you need time for the gelatin to collagen conversion to take place. There isn't much point in raising the oven temperature higher than required to allow the time for this conversion, and it prevents overcooking or drying out the outside of the food while the conversion takes place. The meat will still be quite well done; it is only moist and succulent because of the melted fat, and the gelatin lubricating the meat fibers providing that slow cooked unctuousness.
In a pressure cooker, the ceiling temperature is raised, so the time can be shortened. The inside of the food is still quite well done. No loss to quality (since the food would be well done anyway), but a much shorter time.
If the food was not suitable to be cooked well done, the pressure cooker would be far from ideal, as it would certainly overcook the inside of the meat.
Note also that you have listed two special cases where foods are cooked at lower temperatures to avoid agitation (from the bubbling and boiling of the water), rather than because of issues directly related to time and temperature:
Stock. Stock is cooked at a simmer to avoid the turbulence and circulation from the bubbling and boiling leading to more dissolved, emulsified or suspended particles in the final product. That is, the goal is to keep the stock clear instead of cloudy. If you are not concerned with this aspect, it can be cooked at a full boil.
Beans are cooked slowly for several reasons, of which the main one is convenience. Cooking them at a full boil would require more attention (so they don't burn on the bottom), and is not terribly feasible in an oven, which is the easiest way to do them. Also, by cooking below the boil, there is less agitation in the pot, and so less splitting and sloughing of the bean skins, which some people find less than pleasing.
In the pressure cooker, you will not get this kind of agitation, because once the pressure is achieved and the food is at equilibrium, it is not going to be going at a full boil, but more of a simmer, but a much higher temperature simmer than is possible at sea level pressure.
Best Answer
I got very curious... My test included 4 sets...
Macro Organic Red Kidney Beans from Woolworths Australia selected. All beans were from the same bag... Water was at 18 C (tap/room temperature), 12 beans selected based on similar total weight.
As expected... the addition of salt or bicarbonate of soda increases the efficiency of absorption of water. Your experience will vary based on brand and freshness of the product.
PS My son and I had great fun measuring, pouring and splashing each other with water ... Part 2 is to see if any of these beans will grow... Does anyone have an opinion on whether "organic" beans should sprout and grow?