Has no-one explained it to you yet?
I'll start the ball rolling, then maybe others will chip in with their ideas.
Suppose my assets consist of £100,000 easily obtainable liquidity (cash if you like), £100,000 shares, a few houses to let, perhaps some investments in funds, etc.
Taking the liquidity assets first: you kind of confused yourself, talking about wads of cash and it all being electronic. Of course my £100,000 is not in a couple of shoes boxes in the wardrobe. It is in, say, a instant access savings account. This pays me some interest. It pays that interest to me wherever I happen to be registered. I then pay tax on that interest, to wherever I happen to be registered for tax purposes. I am at liberty to decide where I invest that liquidity. Of course if I am a financial organisation, I must maintain a percentage of my total assets as easily available liquidity, according to the law, of where ever I am registered.
Looking at the shares, of course I do not have a share certificate for each share that I hold. I do not even have a certificate for each block of shares that I hold. It is all electronic, and those shares are registered to me, where ever I choose to be registered, paying tax on those dividends, to whichever government I am registered with for tax.
The houses to let, of course I do not move those houses. They are where they are. But they are registered to me, and I pay my tax on the rent received from those properties.
Get the idea now? Obviously the loss of tax revenue on £9bn of assets will be substantial.
So the £17bn - £25bn p.a shortfall in the public finances, that Sammy referred to in another thread, (
https://www.diynot.com/diy/threads/now-its-honda-leaving.518510/page-4#ixzz5gFXtt9LM ) is partly explained by the moving of assets, and the subsequent loss of taxes.
To put this into context: the chancellor expects to borrow about £25bn this year to plug the hole in the deficit (assuming an orderly transition period).
Now if these assets remained in the UK, and the UK benefited from the payment of taxes on the income received from those assets, the chancellor maybe would not need to borrow this year.........
I hope that helps you to understand the importance of assets being registered in the UK, or not.
Don't forget that the relative difference could be twofold. Not only is the UK deprived of the benefit of the tax from those assets, but another country is now benefiting form that income, making the UK relatively twice as worse off.