I guess it would be smartarse to introduce the Mobius Strip.
Yes, but that's not even the issue with those lift discussions. People want to know "the cause". But physics often just states relationships between quantities measured at the same time, so cause-effect ordering is arbitrary.
Passing trains (or passing anything) pulls air along. You will not get sucked into the side of a train. You might get sucked into the low-pressure wake behind a train, though, but that is a different concept. The water ski analogy is pretty rough. Both an airplane wing and a water ski deflect a fluid down in order to stay up, but that is about where the similarity stops.
Airfoils have a special shape, particularly at their trailing edge. Most of them are "sharp", though it works with a flatback airfoil, too. The important thing is that the trailing edge of the airfoil fixes the separation point at a location that it otherwise would not have been. This combined with the conservation of mass and momentum results in the air over the top being greatly accelerated compared to that over the bottom. The results is a greater pressure differential and more downwash compared to a flat plate. A flat plate at angle of attack (or a ski) doesn't have this action, and so while it can generate lift, it doesn't generate nearly as much.
There's a scale factor involved. For small balsa type gliders, a flat or nearly flat plate wing is reasonably efficient. For gliders with wingspans somewhat less than a meter, a thin symmetrical wing with some tapering at the trailing edge is good enough. Thin airfoils with some camber show up at around 1 to 1.5 meter. At 2 meters or greater, more conventional airfoils are used.
That's not a strictly accurate statement. It has less to do with scale and more to do with the "mission requirements" of each of the objects you mentioned. A small balsa glider can get away with simple, flat wings because it is made of extremely light materials and has no requirements other than gliding. If it has propulsion, like a wind-up propellor, they are generally very large and provide a large thrust to weight ratio. In other words, it doesn't take much lift to keep them aloft, they don't have to haul anything, and they have plenty of thrust, so having an inefficient wing is no big deal. As you get larger, the weight goes up due to materials requirements, internal structure, propulsion requirements, etc. Generally the thrust to weight ratio is likely to go down and therefore, the efficiency of lift generation is more important.
I was making a reference to small gliders similar to this one.
The problem with using this site as a source is that, while he seems to have made a pretty neat balsa glider, his grasp of aerodynamics is at best incomplete. Sure he uses the term Reynolds number a lot (in quotes!), but it is pretty clear to me that he doesn't know what it is.
All of which is in line with what I have been saying. Unless you go to an extremely tiny scale, an airfoil will outperform a flat plate at generating lift regardless of the size (assuming that neither is experiencing stall, of course). If you go small enough to change that, you are likely in the range where we are talking about insect wings, and I am not nearly as familiar with aerodynamics on such a small scale as that.
That is not an issue with Bernoulli's equation itself, as Bernoulli says nothing about why air moves faster. It only provides a relationship. Further, there really isn't necessarily a cause and effect here between pressure and velocity. Really, the two are interrelated and it doesn't really matter which one you want to say comes first as far as I can see. As long as you don't fall victim to the equal transit time myth, then it doesn't really matter anyway.
Outperform is a good description..
The Bernoulli principle describes pressures. Pressure x Area = Force, which is the lift force.