As a fun experiment I grabbed a list of the top 10.000 most popular domains on the internet (according to their Alexa rank) and checked each of them for compression on their HTML responses. Some of them are leaving quite substantial reductions in size on the table by not applying any compression at all.

Some notable entries that caught my eye are the websites of the US Department of State, multiple country specific branches of Lidl, the Python programming language, Klarna and Zapier.