Walk in tubs are not made n Canada but they do have a favourable tariff classification and are duty free to import.
Fact checking Made in Canada claims and other helpful information can often be retrieved very easily using Import Genuis https://www.importgenius.com/ simply type a company name, brand name or product into the search window and you usually see where a product is imported from.
For those with older tubs looking for parts.
Walk in tubs are also manufactured in the UK by https://www.gainsboroughbaths.com/walk-in-baths/ and http://www.wibco.com/ their products were sold in Canada for decades under the franchise names of Premier Care and Seabridge Bathing. The manufactures are still in business making these tubs for those looking for parts. Gainsborough is also a specialty lift bath manufacturer.