Non-rhetorical question: Is this because international travel has always been a major part of commercial flight, while trains spring up in regions? I skimmed a

Non-rhetorical question: Is this because international travel has always been a major part of commercial flight, while trains spring up in regions? I skimmed a couple Wikipedia articles and tolerated the International Civil Aviation Organization's website[0], but couldn't find a group that decided the traveler-facing standards. [0] https://www.icao.int/Pages/default.aspx https://www.icao.int/Pages/default.aspx