Why resolution decides the result
Optical character recognition works by matching shapes. At screen resolution — 96 DPI or below — the strokes that distinguish a 5 from an S, or a त from a न, are only a pixel or two wide, and the match becomes a guess.
Pages here are rendered at 300 DPI before recognition. It costs a few seconds a page and it is the difference between usable text and noise. Tools that skip it are the reason people conclude browser OCR does not work.