Intriguing: people whose deliveries are persistently satisfactory, and others where deliveries often go wrong.
Natural enough to consign whole organisations to hell if they let one down, but unfair on 'Parcel Farce and Herpes' if they successfully deliver millions of parcels to other customers!
I suspect consistent poor service is a local problem. No idea what. When I worked for a living, trouble was caused by corporate setting national pay rates that were too low to attract good staff in expensive areas. This might be a problem in Chatham which has to compete with London pay-rates. Or it might be they're struggling with poor infrastructure because they can't afford an efficient new logistics centre in an area where the price of land is sky high.
Mismanagement is another strong possibility – difficult to do well, and many managers struggle. I'd say bad and indifferent managers massively outnumber the good! Quite easy for bad management to trash a service, either by being too soft, or too hard. Untrustworthy bully-boy martinets are the worst because they alienate the entire workforce and cause bitter resentments that take years to put right – if ever.
In my experience the workforce is rarely the root cause of major difficulties: they tend to react to provocation rather than set out to cause trouble. There's almost always a history of bad behaviour or malfunction such as when companies are badly stressed by staff shortages, high costs, failing to compete due to low productivity, bad investments, poor strategy, bad planning, ineffective risk management, legal changes, trade wars, or are being asset stripped. One exception is small 'c' conservatism: many a British workforce welded itself to comfortable old ways and fought change tooth and nail despite clear warnings it wouldn't end well!
Stupidity is always possible: customers, work-force, management, owners, accountants, shareholders, banks, governments, politicians and voters have all got it badly wrong at one time or another!
Don't know why an organisation like Parcel Force should work well for me and not for others. It's another mystery!
Dave