RE: Amazing payment system in public transport in Bucharest, Romania. This is how it should be. "In Time" sci-fi vibe.

Meanwhile in Porto, Portugal they just installed new interfaces but they don't have that type of functionality. You need their own app to do it directly. It's also way more expensive. The cheapest trip for Metro is over 2€ and same for bus. There are also a bunch of different zones to further complicate things (minimum is 2 max is 6 or 7). For bus, if you don't buy in advance, you have to pay even more for a single ticket that doesn't even allow you to change bus if your route requires you to.