The anesthesizing procedure itself injures the animal in a way that makes it unfit to eat under the rules of kosher slaughtering. I don't know enough about the rules of halal to know if the situation is the same for halal meat.
Plus the anesthesizing procedure sounds rather painful to me. Drowning the animal for 5 seconds while being subject to eletric shock?
They are immediately anesthetized by the electricity, as recommended by animal welfare organizations and ethical councils.
Schächt/Shechita (the Jewish, Orthodox slaughter method not allowing anesthetizing) has been forbidden in my country since 2014. We have a rather significant Jewish community, and there seems however to be a low-key import of such meat, the local legal situation is no longer a matter of much debate (contrary to that of another religious tradition, that of male circumcision).
It is good that there is some progress in animal welfare, though there's also a long way to go. The small-scale, traditional whale killings on the Faroe islands represent such a problem too (The Faroes have a large degree of self-government, are not under Danish laws of animal welfare, and they are not in the EU). They might die out with the younger generations, or international pressure, but a severe pressure from Denmark has not taken place so far.
It does seem a possibility however, that if our societies are generally comparable in say 100-200 years into the future, and we haven't for instance sunk into some new Dark Ages, or some less biologically dependent existence, meat will mostly be artificially produced. Current experiments suggest environmental and cost benefits. It might be combined with a high-quality organic farm sector. Under such circumstances, our current attitude towards animals will likely be seen as barbaric.
