The first company I worked for did equal pay for all new hires, but pay raises and promotions were variable and the raise percentages varied on company performance (so a promotion could be +7% on quarter and then +6.5% the next quarter).

We would all occasionally compare over the years and it would always come up that there would be a small difference (<$1k) where someone happened to hit a lucky streak of getting promoted in a better % year, and people's feelings would be hurt.