Is it illegal or is it not legalized? I think there might be a big difference between those two. Rules and codes can and do change all the time. Just look at UL 3700, which carries the ANSI/CAN/UL designation, signaling Canadian applicability.

It might be even easier now that Canada is getting closer to the EU for it to follow some of their standards as well, like their plug in solar regulatory framework, specially seen that Canada is also a member of IEC (International Electrotechnical Commission), which also covers solar energy

Plus any situation where they make balcony solar accessible will inherently mean rooftop solar becomes availabe and is clearly the more cost effective option.

Keep in mind there are different situations that would greatly benefit from it, like those living in apartments, renters, or where replacing their roof structure for solar panels is more expensive than upgrading a circuit for plug in solar. The market is there, we just need to give it a push by making it legal