From my own experiences of mediumship I have many instances of mental mediumship (Clairaudience) and physical mediumship (Direct Voice) that can contradict this rather broad statement.
I firstly disagree with the statement that 'it takes too much energy for them to come through' .... when it is the medium that is reaching out to their dimension and is using his/her energy to communicate, the communicating spirit uses little or no energy of their own ...
Secondly, a very recent example of mental mediumship communication kind of contradicts the whole statement of mundane matters being communicated by the spirit world (I hate the term spirit or spirit world but for this post I use the recognised phrases) ...
I had confirmed a mental mediumship connection with my client's late mother. For this post I will not go into the details of that connection. However, I will mention, that my client had not given me any information regarding her late mother. I had basically given very accurate information that my client confirmed as being correct about her late mother.
Her late mother then began with 'tell her that I know that she currently looking for a new car',
My client merely nodded in agreement with statement. I then reiterated what her late mother had said to me next, 'she knows you sold your red car and bought the yellow car.'
My client was amazed at this information and had to agree it was correct. Her late mother then went on to tell me that 'you are planning to sell the yellow car and buy a white car.'
My client was now very shocked. She confirmed she currently had her yellow car up for sale and was organising a loan for a white car.
Her late mother then finished off with 'and she doesn't like little cars because she feels claustrophobic, They have to be big cars with plenty of power because she likes to drive them fast.'
My client agreed it was indeed the case. She hated small cars and like big cars with large engines. - Matthew James