And formalised mathematics are ignored in mathematical practice by most mathematicians, and even the ones that know of it often don't use that as a foundational language due to relative inconvenience.
This question seems to misunderstand the topic. The assumption here is not that there is no labor involves, but rather that it its amount is not what determines the value of something it's been put towards.
To me it seems that it's an issue with the political class rather than with economical theory; at the very least, I've seen these policies denounced from the outset by the economists I follow.
I'd recommend Dani Rodrik's Economics Rules that gives you a view of how economists work, what are their limitations and what is their skillset.
I'll try to answer your question through the lens of that book: the models that economists develop work under the models assumptions, and therefore they quite rarely fit well extremely complex phenomena like inflation; in general, economists treat the problems they face on a case per case basis by comparing different models outcomes', looking at the historical data, discussing the merits of the respective arguments for one or the other policy, and obviously depending on the specific goals you find more desirable (equality vs growth for example).
The way the economy is ran is not necessarily representative of the economists consensus, or even that of the economists that are employed by the biggest policymakers, as the policies chosen might be the ones deemed more politically feasible, or more desirable for the particular politician's interests, and not the ones that are economically most sound and well-founded.
By the way, a topic I've been always fascinated by but never inquired further is that of social choice, wherein the economists analyse the incentives of classes such as that of policymakers.
> But even this way, apple devices have by far the longest lifetimes, macs, iphones will have 2-3 owners easily - so is it really fair to call them out, or is it just baseless emotional reaction?
I would dispute this claim, e.g. Apple settles iPhone slowdown case for $500m[1], just the first link I found looking for "planned obsolescence apple" on DuckDuckGo. This is not exclusive to their iPhones as one can find with a quick search.
And you're seriously oversimplifying the situation, lacking in depth knowledge on the topic. Following the news, given the often precarious state of journalism, is not enough to have a "contrarian" (actually mainstream) opinion.
The leave will be formalised, but it won't become completely effective till they will agree on the new trade rules; until then it will act economically as if it were part of EU.