Yes op of course the violin is seen as posh for most people. You learn the recorder at school then you give up and never play an instrument again
In the past, in more places than now, there was such a thing as free instrumental lessons in schools. I benefitted from these myself and would not have done so if it hadn't been specifically offered. I've never been posh or earned as much as the average income.
Singing a few decades ago was an everyday activity in primary schools, and to some extent secondaries, whether in assembly, the classroom or both.
Unfortunately it is up to schools to decide how much music is on their curriculum, and while it is occasionally well supported, in many state schools (both primary and secondary) there is zero music taught.
The local music education hubs offer music lessons and groups in many styles, with bursaries available, but the schools don't always publish the details to parents.
Perhaps they write it off as 'too posh for kids like these' which is a great shame and cancels their opportunities.
If a foundation in music isn't provided in Key Stages 1, 2 or 3 then it's hardly surprising that young people feel alienated from it and it's in steep decline at GCSE and A-Level. This of course is then passed to the next generation. Of course, the unfortunate result is that privately educated young people, with schools that have fantastic music facilities, will end up vastly over-represented in all music genres. An awful lot of pop stars are champagne socialists these days. It's the classical players and teachers who are living on peanuts.
www.theguardian.com/education/2018/oct/10/music-disappearing-school-curriculum-england-survey-gcse-a-level