x out of y to z
y passengers wanted to go to z last month, but only x found a suitable route and were actually transported. This means that ideally x is the same as y. To achieve that, you need to cover all houses at both ends and provide links between them that don't exceed the maximum path penalty (e.g. don't try to transport pax between two neighbouring towns via a complete loop around the map).
Also, "local destinations" is the biggest number, does that mean most passengers in this city wanted to go somewhere else in the city? Now, I've got one station covering most of the city (train station Ctrl-combined to bus station in the center of the city), what happens if a passenger wants to go from x to y in the city where both x and y are in the catchment area of the same station?
The passengers will "deliver" themselves to their destination without paying anything to you. YACD does favour transport though, so if the source and the destination are covered by the same station, but the destination is also covered by another station that has a sane link (i.e. fast enough for the short distance) to the source station, cargo will use the provided transport and not deliver itself.
I have some passengers waiting at Rabourne now, that want to go via Rabourne Central, to Rabourne, i.e. start = destination. That's a bug, I guess?
Nope, not a bug. The final destination shown in the GUI is the town, not the station. Check the "transferring at" lines in the station window, that's where the cargo gets off the vehicle (also if it's final delivery and not transfer).
Another thing I'd like to know is how you get the load balancing into that setup. I never quite understood the inner workings of Yapf and I guess that's where I have to look. Maybe you can shed some light on this.
I forgot something regarding load balancing in the first answer: Cargo packets are also randomly assigned a "transport class", they can be flagged as normal, "prefer cheap", "prefer fast" or both. "Prefer cheap" means that vehicle cost is penalized more (with aircraft being the most expensive and ship the cheapest) and "prefer fast" means that travel time is penalized more. This way you'll have up to four different "flows" that spread out over the network. I implemented that so if there's for example both an air and a train link between two towns, both links are used (imagine business travellers and holiday makers),-- Michael Lutz