It's common sense. It's a common practice in many countries. And we have scientific research to back it up.
I get it that we don't want 60 million people buying hundreds of masks each, and depriving the healthcare workers of the N95 protection for people working in a high-risk situation. But that isn't a problem. We don't need anything special, just cloth masks. You can buy them for a few pounds, you can make you own. You can use an old scarf. You can wash them and reuse them.
The effect is to trap the droplets that you breathe out, to stop a cough from reaching out 5 meters, to stop a sneeze from reaching out seven meters. Even when you just talk, you're spraying our virus particles to a distance of one or two meters.
The point is, they stop YOU from spreading the virus, and if you don't think that you have the virus ... how do you know?
It's like drunk-driving. We don't criminalise drunk driving to protect the drunk, it's to protect all the other road users. You might think that you're capable of driving while drunk, but all the research says that you are not. And, just as you should not have the freedom to drink-and-drive, you should not have the freedom to spread Covid-19, because drunk-driving kills people, and so does Covid-19.
So from June 15th, users of public transport, are required to wear masks. I hope this is properly enforced - by the bus and railway people, but also by the other passengers. "Put that mask on!" should be the cry. Because if you're unmasked, then you're endangering the rest of us.
But why isn't masking required in all public places where there's a possibility of not being able to maintain two meters of distance?