I believe both the wet and dry screen heights were 35 feet ..
Aterpster has the story ...
Originally all were 50ft ... which derived, ultimately, from a very old demo of a Curtiss Jenny (as I recall) into a military parade ground surrounded by trees of around that height. The original US regulator, having to make up some "rules" at the start of the game, figured that was a fair starting point. At least, at an FT course I did many years ago, that was the story told by an ancient FAA certification engineer who was but an office boy at the time.
Part of his discussions indicated that quite a few early rules were little more than finger-in-the-wind best educated guesses by the then technocrats. Some of these persist through until the present day. For example, the maximum stall speed for singles ... originally based on motor vehicle crash damage considerations was a best guess consistent with then aerospace reality ... they came up with 70 mph which, now, is 61 kt.
Later, heavies had the 35ft introduced, regardless of conditions. Subsequently, the sensible reality of balancing stop and go for wet conditions saw the concession to 15ft screen. Much of the history and logic of performance requirements development during the piston to jet transition derives from an ICAO report by the Standing Committee on Performance (early 50s).
It is not a simple case of the regulatory process bending to the will of commercial pressure. All certification, ultimately, comes down to the best rational assessment of risk and balancing risk against what the state of technology can reasonably achieve at the time. This, of course, is what drives periodic tightening of design rule provisions.