A good perspective from across the sea.
However doing passport checks achieves nothing for controlling the "asylum" seekers. Once you are at the passport desk you are already in the country and they cannot send you back to the UK or their home country if they meet the asylum criteria. For this to be effective passports should be checked before departure.
There was an interesting interregnum of a few years where Immigration Officers sat in booths as you exited pier A at Dublin from UK flights, to check those from overseas. If you looked the part and could manage a "Good Evenng" in an acceptable Irish or UK accent then you didn't need to show anythng. They seemed very good at picking out who they wanted to.
Regarding the police checks entering the UK, in my experience these were rarely manned and the few times I was checked was when arriving from Northern Ireland on a UK domestic flight. I cannot recall it happening when arriving from the Republic, although I accept it could happen. It certainly was not every trip.
Regarding the proposed UK universal regulations, I will believe them when I see them. As I said above, either one side or the other side in Northern Ireland just will not accept them however they are done.