One of the interesting things about the pension system is that those with somewhat lower earnings actually get a higher level of benefit from the public system. Given that the system aims to allow people to have a generally smooth standard of living, people at lower income levels actually, because they get more from the public system, tend to have higher income replacement rates in some brackets. So lower salary doesn't necessarily mean less pension. Sometimes it makes it easier to achieve an adequate pension at a lower earnings level.
On the issue of precarious work--and we tried to look into that a bit--