You can have perfect safety with a BR in high and lowsec without cargo scan immunity.The only reason to want it is laziness.
Funny, I see it exactly the opposite. Blockade runner pilots aren't lazy because of cargo scan immunity, but gankers are lazy crybabies depending on ezmode cargo scan to make finding profitable gank targets trivially simple and completely risk free.
Gankers are so greedy they can't tolerate missing out on the occasional juicy target because they're too risk adverse to gank anything they aren't absolutely certain they'd profit off of and too lazy to gather proper intelligence on potential targets. They want their ezmode I-Win button to work on everything.
I have a great idea. Ok fine, let's take away the blockade runner scan immunity just like the gankers are crying for. But with one condition.
At the same time remove cargo scanning completely, take away the ganker's ezmode I-WIN button and make them work for intel to choose gank targets for a change.
It's a win win situation. The gankers would get what they asked for (and exactly what they deserve) plus it'd make a whole lot of industrial/transport/freighter pilots very happy.