Are you telling me that asking them if they are drunk or high because they don't know the answer to your question is no big deal because getting insulted is a part of their job?
In some ways, it IS. The company management often use CS as a shield between them and frustrated customers. They KNOW that by hiding behind their CS drones and refusing to deal with customers directly they expose their employees to a hard time. The best way to attack such companies is to bypass the CS altogether, and bring the battle to the management, even the board. Funny how this often gets results, and the excuse that it was all down to "CS not doing their job properly", and that the offending agent(s) have been fired, retrained, reprimanded, etc along with the customer being offered a goodwill "bribe" to sweeten the apology and remain a customer. This culture means that a lowly CS agent often has to accept the abuse, as standing up for themselves could get them fired as a scapegoat for company failings, and with little or no employee rights in some offshore call centres, they have to suffer.
In the UK, employers have a duty to protect their staff from irate customers hurling insults at them, and any attempt to fire an agent for sticking up for themselves against an abusive customer would result in a tribunal hearing, even a strike. You are therefore far more likely to feel a boot up the arse when insulting/abusing UK based staff than offshore based.
There have been a couple of "secret camera" documentaries about call centres, and it seems that providing a service to callers is NOT their priority. The priority is to get rid of a caller ASAP and mark their issue "solved". This rewards bullshit instead of "I don't know", and a culture of "say what the customer wants to hear if it gets them off the phone quicker". This means that for customers, the impression is that CS don't have a clue what they are doing, and constantly lie and make false promises to get something done about a problem. If called out on it, the company just passes the buck and blames the CS agents for getting it wrong, when it is actually the performance monitoring systems and targets that are the cause. One documentary even showed that some call centre staff were trained to break the law in order to generate additional revenue for the company or call centre operator, this is where "information leaks" come from that customers see as a sudden surge in spam and speculative marketing calls from companies that cannot have obtained the contact information legitimately.
These are not all offshore centres either, many are set up in deprived areas of the UK "up North", where employees are so thankful they have a job that they turn a blind eye to any illegal activity they see, or are expected to participate in. In most cases, if caught, it is the employer that is in trouble, rarely the employees who are pressured into doing wrong.