I have not seen the survey, but if it is simply a list of multiple choice questions and there is no free-format response options then it is nothing more than a survey designed to get the result that the company wants. I doubt it is an email collection exercise since they already have your email address - unless it is just looking for confirmation that you still exist.
Yes these sorts of surveys are generally done to either prove that everything is wonderful, and becoming even better, or to justify decisions already taken.
As an example, a decision was taken to build the new shorter trains without buffets. AFTER the decision had been taken a survey was done to show that no one wants buffets these days.
The following are questions most unlikely to be asked !
"was the train long enough to provide seats for everyone"
"did you find the leg room sufficient"
"was there room for luggage"
Instead questions such as
"Did the catering offer meet your expectations"
"were the staff with whom you interacted polite"
"would you use this service again"
are more likely to be asked as the answers are likely to be positive. Of course the catering offer meets the expectations of most of those using it ! If it did not, they would not patronise it !
Most staff are polite
Most passengers would use the service again. Some have no realistic alternative. Others are probably already repeat customers. A survey probably wont catch that many of those who vow "never again" And by definition those on a train (or those emailed as known customers) wont include those who have decided that trains are unsatisfactory and therefore do not use them.
As an example, I have had very negative experiences of
FCC▸ and considered them to be the worst
TOC▸ of any that I used regularly. No survey carried out on their trains would reveal my feelings as I stopped using them. Neither would an email survey of known customers since I changed my email.