- use good people
- play by simple and clear playing rules
- develop in small increments
- measure progress exclusively in terms of finished functionality
- have a clear definition of 'done'
- enable direct communication between customer and developer
- have a defined rhythm of planing, doing and evaluating
- remove impediments ASAP as they arise
- assure continuous improvement through regular retrospectives
But they haven't. Scrum is radical, it's so different that only companies who are facing serious pressure will really embrace Scrum.
Many companies will do it part way (and that's OK - they'll get some of the advantages, if they do enough of it), but innovative companies with visionary thinkers or in those pressure situations will be the companies who really profit from Scrum: the start-ups, the project rescues (my trial by fire) and the companies facing enough competitive pressure or structural change that it really hurts. These will be the full adopters who get the full value from scrum.
There's more to it than that, of course, but this should help you get started.