Service 3 is a through to Plymouth, via Kingsbridge. Many long routes now seem to be split but actually run through - does anyone know why?
To maintain them as local services - ensuring (as I understand it) that they are not subject to long distance tachograph rules for heavy vehicles that were designed for goods vehicles but drafted such that they include bus journeys over a certain length. My understanding is that whilst safety with monitoring driver's hours with a tachograph is sensible, extension to bus services such as Plymouth to Dartmouth would be silly - and this mechanism (which you correctly say is widespread) keeps the services legal and sensible.
To add to Grahame, a local service route can be a maximum of 50km before a tacho is required.
Operators split routes but run the vehicle through guaranteeing a through service, normally a 5 min stop at the changeover point.
Under domestic rules the full Dartmouth to Plymouth route is well under maximum driving time without a break. They may also change drivers mid route on some routes planned like this.
In Cornwall Truro to Bude sees on some services driver changes at either Summercourt or Wadebridge.
Penzance to Falmouth route is split at Helston.
Usually runs with same driver, tho' in summer it has been know to change drivers on weird schedules.
The bus blind will show Pz-Helston (legally) even tho' it's going on to Falmouth.
Passengers are also confused - "Are you going to Falmouth?".
A few diehards always display Falmouth and risk the inevitable depot notice going up with wording to the effect that is illegal!
There is a 5 minute layover at Helston but you are always late in, so that layover never happens; and as you let passengers off, you have to board the new ones. So no layover for the driver (& don't forget to change the blind)!
Likewise in reverse, Helston is the layover (!) and changeover.
As LiskeardR says, it's all to do with
EU» /DVSA tacho rules, and most
FK▸ drivers come under domestic rules.