There so many things wrong with this statement I legit don't even know where to begin.
Factorio is not a "latest hot indy", it came out in 2013. Its 12 years old at this point. It built a lasting fanbase over an extremely long time, its not a flavour of the week.
Railroad Tycoon and Factorio are not the same genre. They are not even remotely close. Factorio is not even inspired by Railroad Tycoon, its inspired by industrycraft and it didn't even have trains in the early versions because the trains are a miniscule part and some megabase designs don't even use trains to begin with.
Factorio is a puzzle game about setting up automated supply chains based on extraction and manufacturing that can run indefinitely on their own while supplying your factory's defences. You're building a von neumann fortress, not a bussiness empire. The primary gameplay loop has to do with mastering spacial reasoning because you have to individually find the optimal layout for 100 different recipes that use a dozen ingredients all of which you have to make from scratch.
Railroad Tycoon is a bussiness managing game about railroad barons competing for territory and stocks, its about long term strategic planning and resource (physical and abstract) management. The trains don't even function the same, in factorio trains are just one method of transporation and not even the primary one, which is belts, factorio is more focused on automating micro while tycoon is about manually managing the macro.
Resources in factorio are free, you just tap into a new vein if your old one runs out, resource management isn't the primary gameplay challenge.
The fact that you're comparing them means that you've never made it past either game's title screen and are either trolling or throwing random shit at the wall and hoping nobody will call you out on it.