Your correct in that union membership is well down on what it was, your a little incorrect in terming todays unions are a diverse membership, as if that something new. yes heavy industry, which has largely gone is much less, but there always have been a diverse range of trades and professions represented by unions, although some professions of course have their own trade bodies which are sometimes similar and in other cases different.
I'm not sure how home working means you don't need a union? Your completely misrepresenting unions as not fighting for employment rights and working conditions and seemed to have swallowed the Tory line parroted by the right wing media about what it is the current strikes are about. Although obviously pay negotiations have always been a big part of Unions, and that is a focus at the moment, but then so is changes in working practices, redundancies, changes on terms and conditions etc.
Perhaps go on youtube and listen to listen to Mick Lynch, he is both sensible, straight talking and explains what it is his union is fighting for. A little ironically given this thread his Union backed Brexit, but then nobody is perfect!!
I will pick one example at the moment - Avanti West coast run the London to Manchester, Liverpool and Glasgow trains. They rely on drivers working overtime and rest days to run a full service - the drivers have started to refuse to do this, hence train cancellations an a dispute. It seems to me that relying on a workforce to do overtime and work days allocated to rest ALL the time is poor management.
Then of course we come to the barristers - yes focussed on the fact that the government slashed legal aid fees, which means its not worth doing criminal law .
So its not one last hurrah or holding the country to ransom for cash, its defending workers rights, protecting their terms and conditions, and pointing out that the executives and shareholders of many companies - trains, Felixstowe docks, water companies are banking huge salary increases and not the workers.