Thank you for the excellent question.
You're right to note that the source of trade frictions in Canada between provinces stems from differences between one jurisdiction and another in terms of the rules, regulations, standards and so on that a business needs to abide by. Ultimately, that does mean that provinces need to act to smooth out those differences. That's what the Canadian Free Trade Agreement is meant to do.
Currently, through the regulatory co-operation table, it is a slow but important process of identifying barriers, negotiating harmonization agreements or mutual recognition agreements and then implementing them. The federal government can play a role there, first by ensuring that federal regulations that directly affect interprovincial trade are not adding to burdens that businesses face.
A recent example where some progress has been made is agricultural inspection. If you're shipping food products from one province to another, it needs to be inspected by the provincial government agencies and the federal government, potentially adding three different inspection regimes to a single transaction. Having the feds step back and at least trust in the provincial inspection agencies may make sense in some cases.
More broadly, the Canadian government can ensure that the capacity exists within the free trade agreement so that working through the regulatory differences line by line can be done expeditiously. That does take staff in the secretariat. It does mean providing assistance to provinces, especially smaller provinces that might lack capacity themselves.
The federal government can also play a role in ensuring that this issue remains at the top of the national agenda in discussions between federal, provincial and territorial leaders.