This may be a controversial post but this is based off (1) what the devs/website have previously said and (2) my own technical knowledge on software (my irl job).
First, the game is primarily always online as an anti-piracy measure. Despite whatever the devs say, this is the main reason the game is always online. If you are offline for too long, the game doesn't crash. In fact, nothing really changes. Instead, you will get an error about contacting the license server. Rather than implementing other anti-piracy solutions, this is what the devs have gone for. This is where I believe they are not being completely honest in communication outside their website. They give other reasons for always-online, but this is the main reason. Let's all remember the strict computer limits when we bought the game off their website, and the hassle the with the license keys. Most indie games don't have anything like this.
If the devs want anti-piracy protection, this is something that's been solved thousands of times already. Or just be okay with some piracy like 99% of other indie devs.
Second, the game does not need to be always online for any real technical reason. The map issue is easily solvable by allowing users to download them, whatever size that might be. The claim that it's to "get up-to-date data" is intentionally vague. The game would also run better using an offline map since it no longer needs to call OpenStreet Map. I suspect the devs possibly do not know how to make the game work with offline maps. Maybe they have worked on it and couldn't figure it out; or there is something fundamental about how the game was made that it would be a huge undertaking. Either way, it's not a good excuse. It's not that they can't, it's that they won't.
If you think this post is too negative, I want to tell you that If the Subway Builder servers ever go offline, you will never be able to play the game that you paid for again. The game will literally die; killed by it's requirement to be always online. The idea that this single player game could just go offline in the future is crazy. It's not, and should not, be acceptable.
