Maybe? But it's like saying that it's harder to fix a bad country than to leave for another country, so its accuracy is possibly less important than its rationality.

It's a lot easier to switch employers than switch countries. Most people in fact do switch employers multiple times throughout their lives, whereas most people don't ever move to a different country from where they were born.

That's especially true when there are other jobs in the same industry and the same city but at a different company.

That depends on which country you are born into. There are several million South American immigrants living undocumented in the US who would beg to differ with that statement. Likewise, there are many expats who've chosen staying with a company over staying in their country. Finding an employer that treats you well may be harder than finding a country that treats you well in many instances.