What are the legal implications of this? Technically, this would mean this guy's employer is now employing someone in France (or Germany, Netherlands or Spain which are mentioned later). From the employee's perspective as well, they are almost certainly violating that country's laws if they're on a normal tourism visa.
Remote work seems to be an area where laws (in most or all western countries, as far as I can tell) have not kept up. In the above example, you've got a Canadian remotely working for a Canadian company, but living in a foreign country and spending his money there. Assuming he's using a tourism visa like most would be doing in this position, he's breaking the law but this kind of activity is nothing but beneficial to the foreign country, since he is spending money in the local economy, not competing in the local labor market and not drawing any welfare benefits.