Over on Medium, Quinn Norton has a great history of May Day:

Today the vast majority of the world celebrates May Day as Labor Day, or International Workers’ Day. Americans won’t celebrate Labor Day, despite the fact that it all started here, in bombs and blood and hangman’s nooses. By the official fiat, history is remade for Americans: May First is Loyalty Day.

Loyalty Day?! What an insult to the people who struggled, and in many cases lost their lives, for the labor movement.

As Quinn notes:

On May 1st, 1886, labor unions all over America held rallies and strikes in support of legislation for an eight-hour workday, with the slogan “Eight-hour day with no cut in pay.” [...] This was the setting of Upton Sinclair’s The Jungle, a place where people, including children, were often worked to death.

You should read her whole piece.

The idea that workers owe some kind of oath of loyalty to their company is incorrect. Employment is a business relationship, like any other business relationship. That's why one of your goals as a founder has to be to create a mutually beneficial culture.

I'm unashamedly pro-union (as a concept; I do understand that in practice not all union activity is positive, just as not all corporate activity is positive). The labor movement, in common with many progressive movements, has given us lots of things that we take for granted. Stuff like the weekend, and the 8-hour working day. I think American culture has slid back on some of these things, but not in a way that benefits productivity or working culture. The good news is that there's plenty of opportunity to innovate in the structure of companies, as well as the structure of organized labor, and find the right balance.