It's also the law in at least some EU countries, although I haven't checked beyond Wikipedia: https://en.wikipedia.org/wiki/Fill_line
https://germany.representation.ec.europa.eu/news/klarstellun...
Selling drinks in mislabeled containers should warrant a fraud report to your local consumer protection agency. A crowdsourcing app seems like the wrong tool here.
There is some back and forth around whether it's legal to serve beer in traditional ceramic steins, where customers can not verify that the foam really starts above the line.
As I understand, it is legal in Germany, but only if there is visible signage that informs customers about their right to pour their beer into a marked standard glass to check the amount. Source (German): https://www.abendblatt.de/incoming/article402102835/wer-hat-...
In 1899, an association was formed in Munich to combat fraudulent pouring. It was banned by the Nazis and re-formed in 1970. They went around and measured beers. This post is its spiritual successor. German: https://de.wikipedia.org/wiki/Verein_gegen_betr%C3%BCgerisch...