The cold hard fact is that multiple languages on an R/T frequency significantly degrades situational awareness for those not fluent in the language concerned. This has DIRECTLY caused incidents and been responsible for loss of lives and continues to have the potential to do so. How you can overlook this is beyond belief. It's small minded and petty to regard it as a laziness issue when in fact it is a critical safety issue irrelevant to what languages people studied at school.
I am not "overlooking" this issue. I am a native English speaker, but have made a lot of effort to learn French to a bilingual level (I have ICAO level 6) and also German, Spanish and Italian to approximately ICAO level 4 standard. When flying in uncontrolled airspace I always use local language - or else I don't venture into uncontrolled airspace.
I find it arrogant beyond belief that many English-only speakers expect every aviator around the world to learn English - just so that English-speaking pilots can blunder around in their uncontrolled airspace. Do you really expect (for example) every swiss glider pilot - many of whom rarely if ever venture out of their own local valley - to learn English just so that you can fly into their valley?