If by 'They', you mean people paying tax in Scotland, then yes. We pay a higher rate of tax. The process of administering/assessing free prescriptions costs quite a lot (I can't remember how much), it's almost more cost effective to have our prescriptions for free. My friend was involved in the evaluation of the policy, and the cost saving/spend was a fairly small margin.
I do think, overall, we should be looking at how we can make life a little easier for young people (and what do we class as 'young' - given more older students, etc.), but it's not fair to think that everyone over 50 is doing it for their kids. I couldn't have kids, and like a PP, paid a LOT in fertility/IVF treatments. That's fine, I am not complaining, as needed to know that we'd tried.
However, I am far from wealthy. I earn a reasonable salary, but it has a maximum of around £55k, in a University. So, I don't get bonuses, big pay rises, etc. I am now on my own, and won't get my employment pension until I'm 68. I will have my mortgage paid off by then, but on a modest 2 bed apartment. I KNOW I am much better off than many people, but thinking we're all well off, and 'doing it for the kids' really isn't accurate.