I'm sure that there are some full/standing trains - just not as "often" as you seem to experience them
Put it this way, the figures show an average of 135,000 passengers a year at Whitby over the past five years (that's arrivals and departures, i.e. 67,500 return journeys, so 1,300 departing passengers a week), so that means either:
1. This figure is broadly accurate and therefore around 185 departing passengers a day, so each "full and standing" DMU is equivalent to an entire day of passengers
2. This figure is pretty inaccurate, in which case I'd love to know what the true figure is - obviously we're being told on this thread that Whitby trains are so busy that it's physically impossible for Conductors to squeeze down them, and anyway there's a conspiracy because Northern want to cut services even though they could presumably make millions if they ever got around to doing revenue blocks at Whitby!
I'm in the first camp of people - I'm guessing you're in the second?
That's around 185 passengers a day leaving Whitby by those figures.
The capacity of a 156 is 163 (according to Wiki) and if you've ever encountered the 16:00 on a weekday, that's pretty much taken up by the schoolkids. If you add in day trippers, local travellers in the other unit on that train, plus those coming back on the evening train, plus any who are travelling outwards in the morning, then that 185 passengers leaving Whitby a day looks extremely ropey to me.
Put it another way, I've only encountered a full and standing train once between Middlesborough and York (due to a football match) yet that's not taken as a reason why the route shouldn't have a decent hourly service. What is so special about the Whitby line that the fact that it isn't full and standing every hour of every day, is somehow justification for it having a deeply inadequate service that most other routes wouldn't put up with ?
I seem to remember a similar claim over packed out S&C services all year round a few months ago. The reality is of course that there are a few busy trains during the peak times of the year (summer and Xmas) but mostly they are way under capacity (I work the route all year round at all times of day so am in a position to give a more accurate reading of the situation).
I pretty much imagine that this is the same on the Whitby route so will take most of what is said with a pinch of salt.
That's an interesting point, and funnily enough the S&C is another route that I travel quite often.
I have to say, it's a while since I've been on a full and standing train on the route, although I have seen it a few times pre-pandemic. Occasions I recall were a Sunday service towards Leeds pre-pandemic, a morning Saturday service towards Carlisle full of walkers and towards Appleby on the day of the fair. To me, a busy train on the S&C tends to be more likely to be "comfortably" busy, rather than full and standing, but the route does seem to be better resourced in terms of rolling stock, and of course it's timetable is much better, being roughly 2-hourly.