@ ***** I'm starting to think that you have a different definition of "technology doesn't exist" than the rest of us and that's where the confusion is arising. If your interpretation of that is "no one has a working and tested system currently available for use" then yes, obviously "the technology doesn't exist". But I don't think that's the understanding most people would have, and nor is it particularly relevant to the discussion of whether it's a viable option for the future.
If we as a human race never considered trying to use or make anything that didn't already exist ready-to-use then we'd still be living in caves.
There isn't actually any technology available that can be effectively put towards solving this issue.
Just stop to think about what it is this technology would entail before you keep posting. You need a system that:
A) Works regardless if a bowler is bowling over or around the wicket, and regardless of where the batsman stands and how he moves
B) Can identify the moment a front foot lands, and doesn't confuse that with the bowler's backfoot or follow through.
C) Isn't a permanent fixture in the ground (because not all grounds would pay to install/maintain it, and if it cannot be used in every single game of a series/tournament, it's unlikely to be used at all)
D) Doesn't interrupt the game (get in the way of bowlers, batsmen, fielders)
E) Will not break or get damaged over the process of a game, or during bad weather
F) Is accurate and affordable
G) Doesn't require an additional human being present at the ground to operate (you may as well just have a guy staring at the crease whole game via a pair of binoculars calling no-balls instead)
Now, go and actually have a think about what human technology is currently capable of. Look at how other sports tackle similar issues, and see if they are adaptable to cricket. Take the time to actually think this through instead of repeatedly insisting that the technology exists and just no one cbf to do anything, and then then let me know if you think current technology actually allows for a solution to this issue.
Or, y'know, just continue to hold up a protractor to your TV and question why we can land a man on the moon but can't figure out such simple problems.