@duncan_bayne originally they lasted 7 years, and the point was to get people to document and publish their inventions rather than keep them secret like guilds did, and people had a nasty habit of dying with a secret, ala
en.wikipedia.org/wiki/Flexible

Extending patents to 20 years, while technology has gotten WAY better at reverse engineering the formula of Coca-Cola or the 11 herbs and spices in the chicken? That's just capitalist greed.