One of your favorited links is "Holloway Guide Equity Compensation"[1] and it has a section of typical percentages. It also mentions some higher percentages for employees which are not typical.

As for "fairness", it's going to ultimately be in the eye of the beholder. You could give employee #12 a 5% stake (which is CEO level at other startups) and yet that employee still feels it's "unfair" even it's explained that he's getting more than anybody else in SV. It's human nature for the employee to think he's worth more, and for the employer to think he's worth less -- and therefore, they negotiate.

[1] deep link to the employee ownership percentages: https://www.holloway.com/g/equity-compensation#_there_are_no...