Zooms, you must know that businesses cater to serve their largest market. And those vary greatly.
I suspect that >80% of the business done by building supplies companies is to builders and tradesmen who have accounts and phone/walk-in relationships with their suppliers. They don't do quotes and orders through the internet as that would take too long. For them, trying to manage stock and pricing on a website (with an interface to their transactional and inventory systems) would add a level of complication and cost they cannot possibly justify for a tiny fraction of their revenue. Internet-based business for most building supplies outlets in SA is minuscule, and likely to remain so for many years even if they had full online web-accessible systems.
I'm not defending rotten service, unresponsiveness, or uncompetitive pricing. Just saying that your rant against "SA business" is too sweeping and unconsidered.
Most business people I know - small and large - are pretty passionate about and focused on delivering the best value they can to their customers - in a competitive environment that's how you get to stay in business and keep an onion in the soup. And the building supplies business is very competitive, especially with customers who want to save another 1% on things like gutter brackets.