Berkshire enthusiasts will tell you GAAP EPS for Berkshire is misleading because it artificially inflates/ deflates earnings because of unrealized equities gains. Which is a fair point. However, they will be insisting on GAAP earnings and not use adjusted earnings for the other companies. There are clearly different standards.
Berkies would probably agree on a standard for all companies to adjust GAAP earnings to disregard the impact of unrealized gains/losses of equities held for long term investment.
One cannot reasonably accept all companies’ adjusted earnings without critically assessing them. There’s a long history of companies using ‘one time’ adjustments on a regular basis to inflate their reported adjusted earnings when the items they are sweeping under the rug as ‘one time’ expenses should indeed be reflected in earnings that year. Actual expenses, not the unrealized ups and downs of equities held for long term investment.