The argument often put forward by those who support mandatory masks in shops is that it may protect others and we should all be willing to make that simple sacrifice. They see it as a simple case of putting a mask on to protect others and they view anyone who doesn't want to comply as being awkward just for the sake of being awkward. They don't see anything sinister in this new rule and don't realise that it could lead to other freedoms being eroded further down the line. Hence they think that we are just being silly.
Those of us who oppose mandatory masks do so on the grounds that it erodes our freedoms. We realise that this is very likely to be a stepping stone to greater and greater erosion of freedoms. So I think this is the key point in the debate. We need to explain that our main concern about this new rule is not the masks in shops per say, but rather where it will lead. In fact, if we had a cast iron guarantee that this wasn't going to lead to further loss of freedoms (eg compulsory masks every time we leave the house or mandatory vaccinations), then we would not really be that bothered by this new legislation. Those on the other side of the argument have no understanding that this could possibly lead to anything more sinister and hence they embrace it with open arms and think we are just being awkward and dragging our heels for no good reason.
So if we just say that we don't want masks in shops because it erodes our freedoms, they cannot see what we are on about, because they don't see the potential for other freedoms being eroded further down the line. So if we are to win people over to our view, I think we need to explain clearly where we think it could lead to and a percentage of those who have embraced it might re - consider. Some of those who oppose our view might never have considered where this might lead and may be willing to take this point on board if we explain it to them.