Well I appreciate it to the person who explained a few things to me and answered a lot of my questions concerning the Reno Air Race.
With that said, it really is sad that because one has a different view, and asks questions about that view, they are attacked.
To answer your original question...
As others have said, Air Racing and Air Shows are two completely different animals altogether. Someone also mentioned that military pilots are cut from a different cloth. That is somewhat true.... there are different cloths of military pilots as well (not all are great or safe). It may sound weird, but generally in the air show business, experience really doesn't matter as much as everyone would like it to. Experienced guys still die. Military multi-crew aircraft still have air show accidents. Accidents in the air show community are a statistical certainty. The community is very, very close knit and every death hurts.... but it happens... last year was a particularly bad year.
TwoTwoLeft mentioned the ACE card system. If my memory serves me right, I'm pretty sure all military demo teams actually need an ACE card to do aerobatics in waivered airspace. All the demo guys I know had 250' ACE cards. It's not an easy process...especially to keep going past 800'.
The boxes are set up to direct energy outward of the crowd line... there are different lines and corners. Each morning of an air show begins with very informative brief. The Air Boss usually does the brief and, generally speaking, each person sitting in that brief is committed to flying the best, safest show they possibly can. Emergency Procedures are hashed out over and over again. Weather and communication are dwelled on for a long time as well. If you ever sit in on an air show brief, you'd probably be very impressed with the planning, organization, and safety that goes into it.
Getting back to the actual FAA airmen certification on the L-39 and other jet warbirds....
Your friend who was reading the manual sounds like a •. Sure there are rich dudes that buy these, but the very fact that they want someone there to show them the ropes is indicative of something good. You can't just get a wet private and go take a check ride in an L-39. It's not like a normal "Type Rating". The FAA came up with a matrix of requirements specifically for surplus military aircraft that are different for former military pilots and pure civilian pilots. There are few examiners for the L-39, and the examiners are very, very experienced guys that usually only do check rides because they like doing it and want to contribute to the safety of the jet warbird group... they're not doing it for the money or some power/control trip. The guy I did my L-39 check ride with was a very, very accomplished F-15 pilot who was also the test pilot for the SU-27 when Pride aircraft brought them over. He's type rated in many, many aircraft and a fantastic pilot. He also literally wrote a manual for the L-39 that is more in-depth than the typical Czech or NAF manuals in circulation around here. He holds you to a higher standard than any other examiner before. Sure the check ride is ATP / Type Rating PTS level... but throw in some SFOs and other stuff that you won't find on most other check rides. The goal is constantly getting better and more proficient, growing as a pilot through airmanship.
The mechanics are generally the most knowledgable and specialized people you'll ever meet. Nearly each one I've met (and I've been around a lot) knows more about the L-39 and other military surplus / warbirds that most A&Ps could hope to know about their particular machine.
Don't know if that helped to answer your question any... And again, this is separate than Air Racing.