Modern accounting techniques are amazing and super effective,

Hmm

The biggest weakness of accounting though is its inability to capture externalities

Oh so you mean it's actually dog shit then, if you can't properly look at external risks outside the clearly defined formulas and can game said fomulas to cook books to one's liking.

How does one company record the cost of their employees commute? How do you even begin to calculate that? How do you measure the cost of extra leukemia cases in a town ten years after a train derails nearby? How do you record that in your books? How do you calculate and record the distress these huge noisy shipping vessels cause whales? It's just so subjective and impractical.

You act like these are difficult tasks in the modern era. Commute is pretty simple, what type of vehicle, what are its maintenance costs at certain mileages, what are the crash statistics, etc. Once you have a general fomula you can add an increased payout to cover ireegular externalities to properly hedge against the edge cases. Same shit for the others. It's not subjective and impractical, it's just not the going to be perfectly effiecnt as you need to create a bigger financial bubble to account for edge cases. The problem is hyper fixation on extracting the most captial possible from a business. Stop trying to be the most clean cut business and focus on aiding your communities, working to better infrastructure and stop interference with local governments for tax benefits. Then progressive changes can be beneficial to both and reduce external unmitigated risks as we have a more nuanced model to work with.