if you are satisfied with CVS/SVN version - any commit is final and there is no way to undo or modify them - then you don't need reflog. If you mess up, you just say: "oh well this sucks" and leave commit in place. This is what I was doing back when I used SVN and CVS.

hg has similar thing but it's different for each command. For example to undo "hg strip" you manually dig into .hg/strip-backups directory.. I never understand why people call it more intuitive.

Can't tell you anything about bzr, never used it.