Sure.
Many do so indirectly via company or state pension plans but many also do it directly.
For low income earners, the tax breaks given by governments often result in a proportionally more useful freeing up of cash than the very rich (middle income earners usually benefit from these breaks the most though).
Most countries have these sorts of schemes - UK (ISA), US (IRA), Canada (RRSP), etc.
Someone who does not earn a lot but wants to ''climb up'' the financial ladder is well advised to put 10% (or more) of income into such a scheme, especially when they r young.
There is no minimum for people to invest but obviously there r many factors that affect when, where & how much (e.g. minimum deposits, maximum benefit levels, personal needs, etc)