That's nice, but it's not the way the real world works.
In the real world the boss will ask very nicely who is available after hours, and will stress that you have every right to refuse and that it will in no way affect your job or career, and will even show understanding and empathy if you decline.
...and from then on you will be passed over for promotion and when it's retrenchment time no effort will be made to spare you. You will probably never realise why, because the boss and the company will continue being very sympathetic and supportive of your rights.