[coldtea]

>How is it that Apple can keep browsers on iOS this locked down, while there was some sort of anti-trust ruling against Microsoft favoring their own browser on Windows?

Windows was a monopoly. Back then Windows was 96%, Mac 4% and the rest OSes negligible. OS X is hardly 40% of the market (and no, you can't have a "monopoly" on your own platform, as in "but Apple sells 100% of iOS devices").

But even the near 100% of Windows wasn't the actual problem, even with MS bundling the browser. What got MS in trouble with antitrust laws was both having the monopoly AND abusing it by forcing vendors (Dell and co) into special deals.