Gardiner-Liste - simple question

Please look at:
Gardiner-Liste
U28,U29-Ideogramm für Feuerbohrer und Abkürzung für heil und gesund.
http://de.wikipedia.org/wiki/Gardiner-Liste

Maybe I've apologize to people read this forum, but I have just one simple question:
If Sir Alan Henderson Gardiner's hieroglyph list is correct, why do need unsuccessful technological reconstruction-experiments (with wany hours of handworks)?
Maybe is enough to look at drilled and sawed stones, read the hieroglyphs and recognize: ancient egyptians had plazma-like or lazer-like technology?
Excuse me for my english.

This link will get you to the German version in wiki but you can just go to the bottom & click on English.
I am not sure i understand your problem.
A problem there is with Gardiner is his identification of some signs - the only example I can remember off the top of my head is a stork which he describes as a south American stork which is somewhat unlikely.