The ones going towards the Airport don't fill up much but the ones going away from the Airport soon after a flight has landed can have 20-30 passengers on. If a Solo was fitted with extra luggage space it would probably have around 12 seats, so certain services would be packed.
Ideally the service should be free for anyone with a Liverpool South Parkway rail ticket (these are sold by Northern at Liverpool Airport) rather than the £1.80 single charge on the bus, which is around £1.70 extra each way when added to a rail ticket. The Airport could subside this through proportionality small increases in parking charges.
That's no longer true. When 501 went from 3 buses per hour to 4 the
86A ceased to call at South Parkway between 05:51 and 18:55. (Route 501 runs between 06:51 and 18:51)
Bus
80A does serve South Parkway and the Airport all day but goes via the business park and consequently takes 17 minutes opposed to the 10 minutes that 501 takes.