As a CS Cart customer for about 3-4 years now i have to say that even though the support is not free, it's certainly not horrible.
Why do people find it weird they have to pay for a service?
If i bring my car to the garage i have to pay. If my customers want service from me, they have to pay.
Opencart is a free system and they don't support the software except for paid modules and/or bugs, same goes for WooCommerce.
If you want to get support for Magento, better sell your car
since Magento starts at about 2000 dollar a month.
I also never experienced the engineers 'Rude'... just strict.
They certainly don't have any time for humor
But then again... why would they? They did solve lots of issues caused by myself, they had to spend time on and only charged like 10/20 dollar worth in credits. That's not expensive at all.
There is one CS Cart thing that annoys me though and that is how they sometimes seem to ignore the community/customers.
The light checkout is a prime example. For most customers it just doesn't work correctly and the first months they kept ignoring us and there are some basic features that should be part of CS Cart which is only possible with a third party addon.
But support is a thing i've never experienced and they never charged me credits without a solution.