It's the same in most areas, due to automated software as much as anything. If a real person looks at a complaint, it is only to OK the computer response.
Each industry is different.
Most complaints received by a train company do not need individually tailored responses. Many of them are about standard issues (eg. why don't you run longer trains, why not more trains, why are they regularly a couple of minutes late in the morning peak?) for which a pre-planned standard response would provide people with sufficient explanation and would therefore suffice. Given the volume of complaints an average TOC receives, how much do you think is going to cost if each and every single one of the complaints requires a personalised detailed reply? Let's just use a rough figure of, say, 30 minutes per reply, and I am being very generous here. Comparing a train company the size of GTR with a fridge supplier is neither here nor there. They are simply not comparable. Wrexham & Shropshire or Grand Central would be a much more relevant comparison.
A good company is one who trains its staff to properly recognise when an issue needs escalating, and knowing who to escalate it too, so it doesn't waste time sitting in the system while being passed from person to person. Escalating a complaint unnecessarily wastes everyone's time at a big cost to the business. Given how tight finances are at most TOCs, it pays to avoid this happening too often. This also applies to all functions at the business, but primarily at Customer Service who are the ones with access to the bank of standard responses.
I am currently looking into some potential changes to the timetable in response to a customer complaint about a particular connection being regularly missed. This is following an escalation from Customer Service who wanted to find out the punctuality figures for this particular service, and then forwarded to me by my colleague who felt that improvements may be possible to give a better customer experience in the future. These are the issues that genuinely need a tailored response. I am not prepared to be sitting here typing up 20 responses to questions on why we could not simply run more trains everyday, when a standard response will more than suffice, especially when people cannot be specific about which service(s) they are having problems with.
There are some TOCs who do it well, and some who do it badly. Most of the time you will find that your experience depends on who the case-handler is, and what you will likely find is that your experience will vary, just like with any other company.