In Canada, you can get a pardon but you must pay for it after a certain time has passed, usually for minor crimes after 5 years and for major crimes after 10 years. There is a 3 strike rule and certain crimes like murder and aggravated sexual assault on minors which no longer qualify for pardons.
Australia and the UK do not have pardons but for minor crimes, your conviction is usually not erased but you no longer need to disclose it after a certain time has passed, we call this a spent conviction. Unlike the UK which recently reduced the length of time for the disclosure of said convictions, Australia kept the Canadian timeframes which are 5 years for minor crimes or 10 years for major crimes.
Obviously, if your crime was a major one like murder or violent crimes towards women or children, you will never get a Visa to visit Australia. This is a recent change implemented on Feb. 28th by the australian government.
Unfortunately, nowadays politicians leaning right or left seems to believe that punishing people for past indiscretions do not deserve second chances.