How does customer service work with technical services? There is very little time for developers of a system to use on support, so how do you go about building

How does customer service work with technical services? There is very little time for developers of a system to use on support, so how do you go about building the baby padding around them? I would imagine at least 97.5% of support requests are a problem on customers end, so just how much support staff would you need for a global service like this?