Like what standards, exactly? POSIX in its tabs(1) [0] and expand(1) [1] clearly states that tab stops can be wherever, and "every 8 columns" is just a default.

[0] https://pubs.opengroup.org/onlinepubs/9799919799/utilities/t...

[1] https://pubs.opengroup.org/onlinepubs/9799919799/utilities/e...