Which regions of the world prefer mustard in their mayonnaise? I recently moved from Poland to Canada and was shocked to find that I found every mayonnaise I tried in Canada tasteless.

So I compared the ingredients labels of the ones I tried here to the ones I knew from Poland, and the biggest difference I found consistently between mayonnaise in Canada and Poland is mustard, which is not present in any major brand's mayo in Canada, and it's there in every single one that I know from Poland - so I assume this must be the crucial difference.

Then I found out that Hellmann's (one of the most popular brands in Canada, less popular in Poland but still a big brand) version in Poland ("Hellmann's Babuni") also contains mustard - this led me to believe that it is definitely not a coincidence. 

So, what I'd like to find out, is which regions prefer mustard in mayonnaise and which ones don't.

For example, is it a difference between entire Europe and North America, or just some regions? What about other parts of the world? I know mustard is not the only difference, but let's limit the question to this aspect.
The difference in Mayonnaise is varied. For example, in the USA Hellman's and Best Foods Mayonnaise (Same company by the way and same product) add sugar to reduce the acidity. Regional tastes are also taken into account by the manufacturers.

Hellman's mayo in Europe has different ingredient percentages than the same mayo uses for the American market. Many in North America find Duke's mayo to be superior in taste and use than Hellman's due to the ingredient mix. Hellman's mayonnaise in the USA does NOT contain mustard, but there is nothing stopping you from adding a dollop of Dijon in the mix if that's your desired taste.

As a side note, in Japanese cooking where mayonnaise is called for, the most common brand is Kewpie (available in Asian stores and Amazon). The primary difference is that Kewpie mayo only uses egg yolks and also rice vinegar instead of distilled vinegar. It can be used for any recipe that calls for mayo and has a really delightfully more bright taste that's a little different than other mayo's. 

Kraft now also offers Avocado Oil Mayonnaise. Looks healthy until you read the whole list of ingredients. Ugh!

Whatever you choose, you can certainly modify to taste. Bon Appetit!