I think that the nub of the problem is that the customer expectation of service is far in excess of the amount they are prepared to pay in fares for the expectation to be met. The resulting gap has been getting larger and larger over the years.
In the (relatively short) 'golden age' of buses (in reality the 1930s) the job of bus crew was relatively well paid and was of good standing in the community. Bus fares were relatively expensive, and bus travel over any distance was a carefully considered activity for most. Workers tended to live close to their employment, and travelling by bus to school was only for a very few. Traffic congestion and lateness was almost unknown and a trip missing from the timetable (most likely from a vehicle breakdown) was almost a mention in the local paper. During the war and for several years afterwards, the bus industry had to try and cope with an excess of demand over supply. Additional vehicles and crew could not be obtained due to the war effort and its aftermath. Relations between passengers and crew were severely strained. After the war, the wages of bus crew had not risen in line with other workers, and now the job was not seen as a good one. By the mid fifties, staff shortages were causing unreliable timetables. At the same time the country was going through much social change - 'off peak' travel was dropping, not really through any fault of the bus company - workers were not going home for lunch, home refrigerators meant that shopping no longer needed to be done daily, television decimated evening travel to cinemas, sporting fixtures etc. and of course increasing car ownership was particularly affecting weekend travel. All of these reduced the amount of passengers and therefore revenue of each bus, but wasn't really affecting peak period travel, which was still a daily scramble to cater for. Much new housing was built in the 50s, further and further away from town/city centres, in less densely laid out suburbs, but double fares could not be charged for double the costs of provision.
The Licensing system, with its system of objections and expectation that the good routes would cover the losses of the bad meaning that mileage could not be reduced in line with lower demand, coupled with Govt. pressure on the Traffic Commissioner to keep fares increases to a minimum and Govt. policy keeping (particularly nationalised) wages low, has meant that the management pressure on costs has been pretty relentless since the mid 50s.
The 70 & 80s saw massive expansion of private motoring and with it congestion, parking problems, speed bumps and the like, all slowing down bus services and making journey times less and less predictable. The Deregulated era has seen a further raft of cost burden on the industry - Health & Safety, Disabled Access, staff training, Engine emission, Open Data, underfunded concessionary fares schemes and ,the latest, employers NI ; all putting pressure on costs. There is no free lunch - increase the costs / reduce the revenue and see fares rising and services diminishing. We reap what we sow.
The fact is that reliability costs money, and with each percentage point the cost rises exponentially. The fares collected only buy a certain level. Customer expectation is far higher than the level of the fares they want to pay. Buses rely on moving large quantities of customers all paying relatively small amounts , with only a few seconds interaction with a member of staff. There is no money to pay for greater quantity of staff interaction time. There is no money to be paying compensation of many multiple times the original planned outlay (if any) when things go wrong. There is no money for meaningfully increased information provision. There is no money for increased levels of spare buses / spare staff / spare mechanics / admin. staff to get everything right, or for better wages and conditions to attract a better quality of staff at all levels. Faced with a barrage of customer complaint/blame about their unrealistic expectation that only money (or an external agency) can put right, and plenty of complaint from non-customers about the effect of your activities on them, coupled with an indifference by external agencies who no doubt have their own pressures to be dealing with anyway, it is hardly surprising that they take every legitimate opportunity to hand off the blame to someone else!
It is no wonder that the attitude, from management to bus crew, of 'you're lucky to get a bus at all' comes through in the customer service. Undoubtedly there are many good employees, from Bus Crew to Managing Directors who try to do the best they can in the circumstances. There will also be some who, in the nicest possible way, are not so good. But they are all caught up in this squeeze of costs vs. revenue.