Turnover Tax seems to good to be true, is there some catch?

Turnover​ Marginal Rates for 2014​
R0 - R150,000​ 0%​
R150,001 - R300,000​ 1% of each R1 above R150,000​
R300,001 - R500,000​ R1,500 + 2% of the amount above R300,000​
R500,001 - R750,000​ R5,500 + 4% of the amount above R500,000​
R750,001 and above​ R15,500 + 6% of the amount above R750,000​

R750000 turnover and only pay R15500 tax!
And no vehicle logbook or bulging files of invoices etc

So if you are a sole prop and your business has R750000 turnover you will only pay a total of R15500 tax for that year?
Granted if you made a loss it may not be so rosy but most small businesses generally only make income if its profit generating so looks like a win all the way.

Can you be registered for Turnover Tax as a Sole Prop if its a side business and you also earn a salary?