There's no difficulty, the definition could not be clearer, more understood or deliberate.
Thailand defines our status, not the other way round.
We do not become immigrants in a country because we wish it to be so.
If you wish to emigrate to Thailand you have to plan to get permanent residency, which for a man of suitable age, means working for three years and paying tax (among other requirements). The visa system is such that until we get permanent residency we remain transient.
Our visa status is what we are, to wit, 'temporary visitors for purposes other than tourism' is the definition of the non-immigrant visa type encapsulating retirement, marriage and other reasons for visiting here.