The weird part is why weren’t tail lights included in DRLs.

At least Transport Canada, finally thought about it:

New lighting standard

As of September 2021 the Canadian Vehicle Lighting Regulation will require that all new vehicles sold in Canada have one of the following:

• tail lights that come on automatically with daytime running lights
• headlights, tail lights, and side marker lights that turn on automatically in the dark
• a dashboard that stays dark to alert the driver to turn on the lights

This standard will apply to all new vehicles (cars, trucks, SUVs, 3-wheeled vehicles, motorcycles and heavy trucks).