Are multinational companies a public good? If not, why are taxpayers subsidizing their global marketing strategies?

The story is that the Canadian government recently set up food trucks in Mexico in order to promote "Canadian cuisine," which the National Post pictures as follows:

Above: poutine. Below: tourtière, both from Quebec.
(the article says only QC has any sort of cultural food identity. Sorry BC!)  

These national icons are being served from this truck:

Don't judge this book by its cover.

So, the Canadian government has gone to Mexico with a van decorated with fresh fruits...to sell gravy-and-cheese-slathered french fries and meat pie.

To be sure I'm not against either of these foods in principle (so long as the latter is served with maple syrup) and I'm not against Canadians...whether individual or corporate... setting up shop in Mexico to sell the hapless public yet more creative combinations of salt-sugar-fat. (Neither would I be opposed to Mexico imposing Pigouvian taxes on this activity, to compensate for the costly externalities visited upon the public health.)

But I very much object to taxpayers subsidizing the venture. I get that all countries try to promote their culture and in the process increase exports of their goods & services (or is it really the other way around). But as industrial policy goes, this has to be the bottom of the barrel.  If McCain Foods Inc cannot get the word out about its wonderful french fries, I simply cannot see how it becomes the  public's responsibility to provide it with free advertising. 

Last week we learned that corporate tax expenditures more or less equal corporate tax revenues raised in the US.  I haven't seen similar number crunching for Canada (working on it), but I expect for multinationals at least the story is very similar. If you then add these straight up subsidies, are we getting to a place where multinationals constitute a net drag on the fisc? If yes then we should be asking ourselves: when did we decide that multinational corporations are a public good that must be financially supported by other taxpayers? 

Is there anyone out there still clinging to the sense that a free market economy must mean something other than government subsidies for favored industries?