You are absolutely right: for years, CUPW has been suggesting that Canada Post extend business hours so that the public can go to post offices. The corporation has persisted and still claims that it is day customers who will go to the post office in the evening, which is false. Customers go to the post office to the extent that business hours suit their schedules. The collective agreement permits a change of working hours and resulting working conditions.
On September 26th, 2016. See this statement in context.