This is how it is currently in SA. They start formal schooling in January of the year they turn 7. A lot of times, they don't start until the following year, the year they turn 8 as those with birthdays in November or December are essentially a year younger. This has to be motivated though by the pre-primary and education department. There are some instances where a child starts earlier, but this also has to follow the same procedure.
Pre-primary is not classed as formal schooling, and only some primary schools have an pre-primary class. Usually this is a class at crèche or day care. It is encouraged though. I have read that within the next few years all pre-primary classes will be linked to a particular primary school.
Having had one child start school in UK at age 4 and one child start schooling in SA at age 6.5, I personally feel the system here is better as my ds was most definitely not ready emotionally at age 4 to start school.
We pay school fees for state school (but this does depend of the type of school in your area, this is a whole other thread) so financially there is no pressure to send children sooner as pre-school and school fees are about the same.