The companies do not have to do this. It is purely optional, though there is a tax advantage I believe. Most "professionals" have the option at their company.
A bigger problem is that the 401k offerings are fairly bad usually. The people picking them are HR staffers who frequently don't have experience in finance, so the plans frequently have murderously high expense ratios. Even to the point where some companies repackage Vanguard funds that you can get on the open market for 10x less.
total employee and employer contributions (including forfeitures) - the lesser of 100% of an employee’s compensation or $54,000 for 2017 ($53,000 for 2015 and 2016 not including "catch-up" elective deferrals of $6,000 in 2015 - 2017 for employees age 50 or older) (IRC section 415(c))
So the max is basically 200% match of the individual's contribution, which is maxed out at $18,000 for an individual under 50.