This is not a fictive fine, it's threats of imprisonment, and ignoring the whole thing means having to avoid travelling to or through the UK for life, and that's assuming the UK doesn't try to activate any sort of extradition agreements.
Even without going to prison, that's a permanent and quite significant theft of freedom of movement. If you ever travel abroad, you could end up accidentally booking a transfer through the UK.
No one ends up unintentionally transferring through Russia anytime soon. And likening the legal threats of a foreign nation to a joke from your neighbor makes no sense.
Russia is a well known authoritarian state arbitrarily penalizing anyone not aligned with and assisting their ideals, with no expectation of any kind of fair process.
The UK is a misguided democracy within the usual group of countries considered "the west", enforcing stupid and broken laws in a highly questionable fashion that presents fundamental questions about jurisdiction in the modern world.
However, it is acting against an entity is cancerous enough that even the defendent is purely challenging (and getting support on) the technical legal grounds in a search for precedent.
If your flight is redirected due to weather/etc. to some British commonwealth country, then you might be grabbed upon landing. Or if you are a really big fish, your plane might be forced to land on a crown-controlled land.
The only member of the Commonwealth that is British anymore is the UK and any of the independent countries in the Commonwealth grabbing a passenger on behalf of a civil judgement in a English court seems no more likely than any other random country doing so.
Even more unlikely is the crown exercising the kind of power you're talking about. Never mind that Charles isn't the King of the majority of Commonwealth countries.
This is not a fictive fine, it's threats of imprisonment, and ignoring the whole thing means having to avoid travelling to or through the UK for life, and that's assuming the UK doesn't try to activate any sort of extradition agreements.
Even without going to prison, that's a permanent and quite significant theft of freedom of movement. If you ever travel abroad, you could end up accidentally booking a transfer through the UK.
No one ends up unintentionally transferring through Russia anytime soon. And likening the legal threats of a foreign nation to a joke from your neighbor makes no sense.