Local taxes do and are applied as the purchaser is in the UK.
You should look at the invoice Apple gives for an App Store purchase.
It includes an item giving the VAT amount of 20% in the UK.
and ends with
Copyright © 2022 Apple Distribution International Ltd.
All rights reserved
Hollyhill Industrial Estate, Hollyhill, Cork, Ireland. VAT NO. GB117223643
A bit more research and memory says that all digital downloads by UK customers have to charge VAT.
See the UK Government's VAT rules for supplies of digital services to consumers
Many third party payment providers do provide the service of charging and collecting VAT (e.g. from my recent purchases Paddle, Fastspring) However looking at my invoices US companies that have their own payments portal seem mainly not to charge, I think they are breaking the law but then again how would UK or EU tax authorities be able to make them pay.