Train lines cost hella money to build. There's no point building a new one for maybe 100 people to regularly use. The road network is so interconnected that people from many places can use the same roads as part of their journey, but if each journey was to be completeable by rail, my country's entire tax revenue for several decades would have to be spent building it.

I keep finding cost comparisons for 6 lane roads vs railroads where the railroads often come out winning, but the reality is, my country doesn't really do 6 lane roads. 4 lanes is reserved for SOME sections of the big highways, but mostly it's 2 lanes, and sometimes you'll even see some gravel roads. There are very few places where the raw throughput of rail is required, because most settlements in our country are literal villages. There's a few decently sized towns and when you run out of those, it gets small and spread out very fast. We have just a tiny bit more area than the Netherlands, with less than a tenth the population.

Would I love to live in a train utopia where you can get everywhere via rail and maybe an electric scooter for the last few kilometers? Absolutely. But it's simply not affordable, so we have 4 or 5 main lines to cover the low hanging fruit. The rest would have increasingly diminishing returns to implement. Actually there are two more lines that could be implemented to get the connectivity to cover a significant part of the population, but they'd be pretty expensive, lots of marshland areas to go through, etc. And it still won't help most people living in small towns spread across the country. I do hope those lines will be built, but right now there's nobody talking about it. Right now they only want to electrify existing mostly non-electric lines, add more trains on existing lines, and increase speeds. So there's definitely more to be done that is also not being done. But I don't think the country will ever be fully covered by a rail network, many lines would just be running empty most of the time.