Marriage does seem to be something which is increasingly a class-based thing. I'm not speaking about the older generations where marriage was common across all groups, but amongst those who are under 45, people are far more likely to marry if they are middle class.
This is partly why some people think marriage is old fashioned or doesn't happen- because they live in areas or mix with people where few are married and very few marr in Church. If you go to most independent schools you will find the parent body are almost entirely married (or have been).
I think it's really interesting that people decide marriage is old fashioned or weddings something of the past. It suggests to me a very narrow experience and social group to think that and also only an awareness of an extremely limited time period. Things are changing, but more slowly and less extensively than some people seem to think. Individuals may personally choose not to marry but there is still widespread support for marriage across society and particularly amongst the more affluent.
And going back to the school wedding in Church thing - it isn't the Churchbwhich push this. Study of the Church is on the school national curriculum set by government not the church. It's hard to believe that anyone would think some kind of study of the church should not be included in the curriculum, even if you aren't religious - I'd have thought most people can see the church has been hugely important in society in the past and whatever anyone thinks personally about it, still has a role today. Therefore children should know about it, unless we are saying they should only learn about a narrow range of things which fit our personal interests. They also learn about other religions, but by the age of 5 will of course had limited exposure to any area if the curriculum and it's not surprising they start with the Church and not the Synagogue when it is something more children will easily relate to. So the Church and some basic ceremonies such as marriage are laid out by the government as topics to be covered. Primary schools love to make learning active - dressing up, role playing, out on site if possible - evidence suggests it all helps learning. So most schools will visit a church - it's usually a very easy,mlocal trip. They will look at features such as stained glass windows and the font and they might or might not role play a church ceremony. They could look at communion or baptism but for 5 year olds, a wedding ceremony is usually something they can understand and find more interesting. It is a learning experience, not a telling them that everyone must get married or married in a church. I'm amazed that people can't see the difference between a government-led curriculum topic and something being what they seem determined to see as church indoctrination.
I suspect that one of the reasons some people feel uncomfortable with this, is simply because a church wedding is outside the realm of experience for some people and that things outside their experience make them feel uncomfortable and go back to prejudices and misunderstandings of that thing. So people don't actually ask questions and gather facts about what is going on but make assumptions - it must be the church pushing an agenda, it must be saying everyone should marry, it must be excluding all other religions or not teaching diversity ........