Typewriters traditionally have monospaced type which means every letter whether a /i/ or a /w/ capital or not occupies the same horizontal space. A double space after a full stop (period) assists reading legibility.

Computers in these days of the GUI have proportional spacing so the width occupied by each character, including punctuation, varies accordingly. Legibility built in!
Traditional typesetters used bits of lead at varying widths (designated in ems and ens for obvious reasons) to achieve these asthetic subtleties.