They achieved this in Australia by saying "we don't care how you achieve both security and putting backdoors in, just have a 'capability'". If you don't have the ability to open a backdoor for them you've committed an offence

The best counterargument I came up with at the time is the security of our children. Who the hell knows what teenagers are sending to each other these days? Do we even want to know? I don't, and it's weird that Attorney General Barr wants to open this door. Why risk letting the wrong person sneak into a position where they can see all of our children's messages, everyone deserves real security