The Growing Imperative for Internal Free Trade in Canada

This seems to be an interesting approach! It may apply also to other countries that are federalist.

"... According to estimates, interprovincial trade barriers add between eight and 14.5 per cent to the prices of goods and services in Canada, which implies direct economic costs of around $32 billion a year. Barriers to trade and labour mobility also contribute to slower productivity growth in the economy.

Prominent non-tariff internal barriers to trade and labour mobility in Canada include dairy quotas, restrictions on the sale of alcoholic beverages to customers in other provinces, and sector-specific regulations that differ across provinces/territories, particularly vehicle weight and dimension standards.

The federal government should encourage the provinces to liberalize trade within Canada ..."

The Growing Imperative for Internal Free Trade in Canada | Fraser Institute