Furthermore, the owner does not and cannot give you any warranty whatsoever, even if this would be run on membership fees not advertising clicks. Im all for OP first website project and kudos for doing something beautiful and even more so getting it up on HN this high, but this site should not exist. Without this site there is more chances that someone who seeks this info will endup on legitimate site - hopefully government run or airline run, and not take this at face value and move on with packing their bags.
Yes misinformation is dangerous, but the author certainly could link to airline sites, the official government travel information websites for each country, and wikipedia and other resources. If you can't even think far enough ahead to come up with these constructive suggestions, then maybe you should try harder or just not comment.
It's not overly harsh. When the cost of being wrong is this high, then this site (or any such site) should not be publicly available until it is reliable.
On top of that if people travel by train or other means it's not that obvious to look on the website of some airline.
Also it's someone sharing their site in a Show HN, constructive feedback (missing data, wrong information) would be helpful but "Why was this even a website worth posting about?" is not.