I was on the website of a bank. I patiently slogged through all my details, not forgetting mother's maiden name and name of first pet. With a sigh of completion I finally clicked submit. "We're sorry, our system is down this morning. Please try later." Er, couldn't they have warned me before I started? I did log in later, went right through the whole rigmarole and finally received the bank statement I needed.

I could have left it there but I was feeling public-spirited. Mightn't my experience help them make their website more user-friendly? So I telephoned. A succession of courteous robotic voices led me to an equally courteous human. And now here is my point. I was trying to benefit other bank customers in general. She thought I wanted satisfaction for myself in particular. It appeared to be outside her comprehension that somebody might take the time to make a public-spirited suggestion to help other people.

"May I call you Richard? How may I help you, Richard?"

"Well, I've been on your website trying to get a bank statement, and I'd filled in the whole form before I was told that the system was down anyway. Could I suggest … "

"My apologies for that, Richard, let me help you now. What exactly is it you require?"

"Er, no, I don't think you understand. I've already got what I personally needed. I want to report the difficulty I had, so that you can make sure other people don't suffer the same inconvenience in future."

"Richard, please tell me what is the date of the bank statement you need, and I'll have it sent to you."

"No, I already have the bank statement I need. I'm trying to help other people in my situation … "

I might have been speaking Volapük. She simply didn't understand a word of Voluntary-Public-Spirit.

On another occasion, in 2009, I was commissioned by Prospect Magazine to fill its regular slot on "If I ruled the world". I wrote it on a plane, and began with an incident I'd just witnessed at Heathrow security. A young mother was distraught that the tub of ointment she needed for her child's eczema had been seized.

"The security man was polite but firm. She wasn't even permitted to spoon a reduced quantity into a smaller jar. I couldn't grasp what was wrong with that suggestion, but the rules were unbendable. The official offered to fetch his supervisor, who came and was equally polite, but she too was bound by the rulebook's hoops of steel. "There was nothing I could do, and it was no help that I recommended a website where a chemist explains, in delightfully comedic detail, what it would actually take to manufacture a workable bomb from binary liquid ingredients, labouring for several hours in the aircraft loo, using copious quantities of ice in relays of champagne coolers helpfully supplied by the cabin staff. "The prohibition against taking more than very small quantities of liquids or unguents on planes is demonstrably ludicrous … one of those 'Look at us, we're taking decisive action' displays."

Once again my motive was public-spirited, and now there was no question of self-interest because the fated ointment wasn't mine. The woman's experience had been a particular peg on which to hang a general point. Unfortunately, when I returned to make a similar point on Twitter this week, I foolishly chose a peg that was vulnerable to misinterpretation as self-interested. And the result was a puerile display of sniggering frivolity such as only Twitter can serve up.

This time the dangerous explosive was not eczema lotion but honey. And it belonged to me, at Edinburgh airport, bound for Heathrow with only carry-on luggage. Though the jar was small, it exceeded the limit laid down by the rule-happy officials of airport security, and it was thrown away.

I tweeted to the effect that every time I see an incident of this kind I sense it as a victory for Bin Laden. However calamitous the destruction of the twin towers, doesn't the bureaucratically imposed vexation to airline passengers all over the world mount up to a prolonged and distributed, albeit far less traumatic, victory? And aren't our rule-merchants playing into Bin Laden's dead hands by their futile displays of stable-door-shutting?

But because the honey was mine not a young mother's, my motive could surely not be other than selfish. "Stop whining about your lost honey." In vain did I protest that I couldn't give a damn about my honey. I was making a point of general principle, trying to be public-spirited. "If you weren't so ignorant, you'd know the rules about liquids." In vain did I reassure the tweeting twerps that I know the rules all too well. That's precisely why I'm campaigning against them.

I say nothing of the feeble jokes on "bee" and "be" and Pooh Bear. My point here is the one brought out by my encounter with the bank clerk. What is it that renders some people incapable of conceiving how a person might be motivated not by narrow self-interest but by a public-spirited concern for the common weal?