I don't understand why you don't understand tbh.
The evidence is now there that masks will help slow down the infection rate, by cutting down on one way it gets transmitted.
We are going back to work. People who are vulnerable deserve to be part of society, or we should plan to open old style community institutions, because being isolated is killing people. So we need protection. Masks provide that.
Global travel is happening, so our R rate can change at any point. The scientific community seems sure that we will get a winter wave, when everyone wants to hit the shops. Likewise people are still hoping for Christmas Markets, Theatres, Panto etc. We are preparing people for that.
We need money circulating in our society and that includes the high Street.
Ten days is so people can get masks sorted. No doubt food banks and community groups will get them, for people who can't afford food, let alone masks. Likewise care providers, social services etc.
Every child in countries that already wear masks is learning to live with it. Ours will to.