Do you believe in any tax? All of it comes from something somebody has ‘earned’.
I believe that all tax should (in theory) be avoidable and only paid 'knowingly'. Although, in practice, you will end up paying a lot of tax, it's because of life choices that you've made - often very good, worthy, wise choices (or realistically Hobson's choice), but still ones that you could have avoided if you'd wanted to.
Deliberately earn only within your personal allowance to avoid income tax; buy only very basic, spartan goods that aren't VAT-able (easier said than done, I know) - or even grow your own food/make your own clothes; don't run a car; don't buy any insurances etc.
These are all things that, if you were to do them, the taxman wouldn't have a say in, but if you own a house over the IHT threshold (difficult to end up doing if you've made some of the abovementioned choices, I realise), the taxman WILL force you (your estate) to pay tax by default, unless you deliberately retrospectively make arrangements to thwart them.
I think IHT is inherently a thoroughly ageist set-up. Many people in care homes are, at least partially, subject to medical health problems, rather than just general/personal care needs.
If a 10, 20, 30, 40-year-old person had the same needs, there would be no question that the NHS wouldn't pay for them, with nobody sniffing around to see what property could be taken from them or their parents to pay for it; but just because elderly people will often own their own home outright, and their death is likely not to be too far into the future, they're seen as ripe for the plucking.
Even if they are only general individual/dependence needs and non-medical - so we adjudge them out of the remit of the NHS - how is that different from the NHS covering all of the costs of a 'textbook' birth, where there are no active medical concerns other than what could potentially befall the mother and/or baby - just like numerous medical problems are considerably more likely to befall the elderly? Should the government be looking to put a charge on the expensive house of wealthy parents in order to pay for what are normal and anticipable 'beginning of life' costs? What if that same wealthy family go on to have 10 straightforward NHS births - why shouldn't they pay for what is mostly non-medical-need and very much predictable costs? Where are the people demanding to know 'why should I have to pay for other people to have more children than I could ever afford to look after?' and thus demanding they be personally taxed for their own families' needs in that respect? But flip it to the other end of life, and it's 'only' the old folk, so we don't want the burden of their needs.
I also think it's disingenuous to say that it's different because it's taking assets from a dead person who no longer needs them. Those of us with children - or those without who are also community/philanthropically-minded - don't make choices in a vacuum. We choose to leave legacies to the younger generations, often making great personal sacrifices whilst we are alive in order to do so. A deceased person's assets aren't just 'random' money that's dropped out of from nowhere - they are the proceeds of their life's work (and, yes, sometimes luck or being in the right place at the right time).
Meanwhile, lottery jackpot winners aren't taxed on their multi-millions, because they already paid 40p or whatever tax when they bought their ticket, so it's considered inherently unfair to tax them 'again'. But when you've paid lots of income tax (often off the back of hard work and sacrifice) and VAT in getting yourself comfortable and amassing a few valuable assets, it somehow is fair to tax you again on it.
For the record, I'm not wealthy and none of my family have ever been (or likely will be) anywhere near the IHT threshold, but I think the whole system is grossly unfair and discriminatory in a huge number of cases. Maybe somebody should campaign against it and take the case right up the top, to the King, as surely he will understand fairness....