Off the top of my head..
1) Require people to prove they can drive on a motorway before we let them drive on them. You can get your licence and immediately drive at 70mph down a motorway despite no-one ever giving you any instruction or examining your ability to do it safely. You can't drive down a 30mph road past a school or a NSL dual carriageway without it but you can on a motorway for some reason.
2) Stop allowing people to drive on foreign licences for extended periods. e.g: You can pass you test in India by driving 50 yards, turning left and stopping, and this entitles you to drive in the UK for 12 months. Mexico doesn't even require a test to be taken, but you can drive in the UK for 12 months.
3) Require a refresher test every 10 years at the same time as renewing your driving licence. Things change over time, some people who are driving now passed their tests before motorways even existed in the UK. One of the problems with smart motorways is that people who don't often use them don't understand what they are or how they work.
4) Have dedicated traffic police, and more of them. And not dragged off to fill holes elsewhere. How often do you see police out on patrol or acting as a visual deterrent compared to a decade or two ago. Multiple studies have shown that the chances of being caught have a larger impact on people behaviour than the penalties for being caught.
5) Stop relying on technology to police the roads. If your vehicle is taxed, insured and you slow down for speed cameras your chance of being caught for drink/drug/dangerous driving/texting is virtually nil. Even if caught on dashcam you're unlikely to be prosecuted - one look at the amount of dashcam footage uploaded to the internet shows the amount of times the police haven't done anything as the driver couldn't be identified.
In a normal year I do about 50-60k, mostly on the motorways. I see the benefits of the smoother flowing traffic and reduced delays they've brought.