There are some good questions relating to what constitutes mechanical devices. The biggest problem is that technology is advancing faster than the law can keep up with it. It seems that no sooner does a law go into effect for one new item that five more appear. The process to either legalize or outlaw each and every item that appears on today's market can come close to overwhelming any fish and game agency.
Trying to simplify my answer on the turkey where you pull the string or the climbing tree stand--the movement is accomplished by your (human) power not by power supplied by another source.
A couple of years ago I was talking with Dave Holt (Techical Editor for Bowhunter magazine) reference laser rangefinders. At that time the considered opinion was that they would be illegal to use since they cast an articifial light on an animal (which is illegal under our spotlighting law). Dave gave some good arguments on how you could possibly get around it. The ultimate decision was that they wouldn't impact the resource. The hunter would have to "shot" the animal with the range finder, put it down, and then still either use a bow or gun to take the deer or turkey. A laser sight is still illegal because it is casting an artificial light on the animal will in the actual act of firing.
The same reason (not impacting the resource) was the reason for allowing the use of game tracker type cameras. Granted they showed pictures of some nice deer and the time and date where posted on the pictures to let the user know when the animal came by. But, that sure is no guarantee that the animal would be back again at the same time and same place.
It would be nice if every item currently on the market or in someone's drawing board would easily fit every fish and game agencies definitions of what is legal and what is not---but in reality there is some gray areas, and we (the DNR) do try and address them when they are brought to our attention. But as I said earlier, the process to deal with each item takes time, either through trying to pass a law or deciding if it can be dealt with within the Iowa Administrative Code (IAC). This type of action has to be cleared and approved by our department heads and division chief before it is even brought up to the Commissioners. Then there is the time for public input, either pro or con, and then an decision is ultimately made.
I know this is a rather long winded reply, but it is a lengthy process to deal with new items.
And, as Tony stated, if you don't like something, nothing is always set in concrete. If you have some concerns let the DNR know. Call and talk to the people in DM, or write letters. Be articulate, explain why you think a change should take place (either making something legal or illegal) and if you have friends of the same mind set get them to write letters also. Don't ever send in petitions--they will go nowhere. Individual letters make all the difference in the world.
Doug Clayton