"SSB claims they want a less time-consuming way of collecting and analysing household consumption statistics in order to inform tax policy, social assistance and child allowance." Aka the more we know about you, the more efficiently we can create policies to control your behavior to our liking.
You're already being tracked by the grocery stores, wouldn't it be better to be tracked by someone who at least tries to have your best interests at heart vs. the grocery industry who just wants to sell you more?
Oh man, if somebody with the power of a state tracked everything I did in order to improve my life, and for no other reason than that, I would love it. Sounds like a guardian angel. Sign me up.
But... what if they didn't care about me very much, never really thought of me at all, and really just saw me as one person among tens of millions? What if instead of helping me, their main motivation was to get re-elected?
And what if the government in power was somebody I actively didn't like, and had even protested against? Maybe I felt they were evil and irresponsible. Would I still want them tracking me and trying to change my behavior?
I can think of people I would want to give that kind of power to, but it's the people I don't know about yet that worry me.