You postulate this as if this is the biggest blocker for business in this country?
But why do you think this is a problem?
Every country in the world has customs, most are significantly more onerous that SA (especially EU and to some extent the US also)
And what import restrictions do you mean, because I literally buy stuff daily from other places in the world.
I have deliveries near daily from overseas, I order from Amazon.com, AliExpress, eBay, Digikey, RS, Mouser, etc. constantly.
Some courier, some post office.
To date, not a single thing has ever been denied or restricted by SA customs.
I've even had wrong assessments by customs and sent it back and STILL got the parcel with significantly reduced customs.
SA customs doesn't care unless it is on a restricted list, like firearms, nuclear materials, animals, plants, etc. (thing you can probably buy with a permit anyway).
They just want their cut, that is all they are about.