For example, religion to a modern protestant-descended American means something very different to a Salafi Muslim. To one, religion is law. To the other, it's superficial pomp.
If your ancestral law (Salafi religion) dictates that you will slaughter animals a certain way lest the wrath of God and your kin and your ancestors strike down upon thee with great vengeance and furious anger, that to violate such a tenet is to violate the law, then by God you will do it.
A rationalist (protestant religion) might divine the religious practice has roots as a hygienic practice that was useful for stone age peoples in a desert climate, but today has no practical use, and he might be right, but that doesn't matter to the Salafist. The Salafist's "why" for doing things is very different and much more personally compelling than the protestant's "why".
The protestant would be well-served in realizing that, although he distinguishes religion from state or law, many others in this world do not.
For instance, if you curse at your parents, the Old Testament calls for you to be stoned to death. This one is conveniently overlooked though
How many Christians have you ever seen laying hands on bodies at funerals, trying to resurrect the dead?
There is plenty of common sense in the holy books.
It could not matter less that the advice given in these books used to make sense at some point.
Some religions evolve faster than others. I would hope the different faiths can come up with iterative improvements to their standard operating procedures that still meets the requirements. I believe the Jewish religion even has a concept about creatively outsmarting the religious rules as being a virtuous thing (eg women wearing wigs).
But my question still stands, specially on the light of such view of religion: if religion is, these days, meant to give people internal piece, does it need to dictate such practical things as how you should kill animals?! How do you reconcile that with your view on religion?
This assumes literally everything is different today. Which of course is nonsense.
How could you use "hygiene" to justify the unnecessary torture of animals with outdated butchery techniques? 2000 years ago there probably were great health reasons for doing so. We're in 2021, there's simply no excuse.
Circumcision probably had hygienic benefits back then, too.
But we no longer live in these circumstances.