I get what you're saying but look how absurdly difficult it is to make high speed rail, the UK are no strangers to making trains but HS2 has been a huge disaster with endless extra costs, ecoprotesters delaying it and etc - it's currently expected that stage one will open between 2029 and 2033, they started planning in 2009. Rail is not a quick and easy solution, it's also cost £100 Billion and the options to upgrade it are incredibly limited.

Meanwhile in Washington state they're building a facility which uses carbon from the air to make jet fuel, the us military already tested it in all their jets and it works great - it's not especially difficult chemistry so likely to be commercialised at a competitive price point. It doesn't require engine modifications or anything like that, can be made with excess power from renewables at peek times to lower the cost even more and make wind and solar much better investments.

We've been using blended biofuel in aviation for over a decade without anyone really noticing, we've also been switching to electrofuels - Obama created ARPA-E the same year HS2 was unveiled, they had some significant successes such as using co2 as the fuel source (though got shifted to focus on fracking without anyone caring which is a real shame). There are various projects around the world creating efuel already with plenty more in the planning and development stages.

It's not a perfect solution but it's an actionable solution and a great stopgap, it could even be the boost carbon sequestration needs to become a profitable technology which leads to new markets being established and us actually starting to pull measurable quantities of carbon from the air.

I love trains and I hate flying, but if we can make carbon neutral fuels then being able to zoom over the top of beautiful ecosystems rather than dissect them with steel rails would be better for everything, building all the infrastructure for a giant rail network would create huge amounts of emissions and take decades to get to the point where the daily savings Vs cars has paid off, it would put us deeper in the hole and probably way past the point where net zero can help.