I think you’re misunderstanding the use of the term “public” here.
A mall is a public space in the sense that people can go, but it’s not a public space in the sense that it’s not operated by the government, it’s a private space.
I’m using the term public space in the governmental sense, not in the publically accessible sense. If you use that definition of public I’m pretty sure even in your country you can get censored and kicked out of a mall and moved off its surrounding property (the parking around it), because it’s privately owned. Once on the sidewalk you’re on public property though so you can do whatever you want as long as it respects the law.
Also, talking about Europe as a whole is wrong since different countries can still have different rules on the subject.
Trump will be able to enter Canada just like Bush was. There’s paperwork to fill, the process is available to anyone from the USA with a criminal record and that wasn’t to visit Canada, the paperwork was filed every time Bush visited, the border service agency just needs to approve the visit (which they’ll do for Trump).