Maybe its just me ...

Received a letter from a potential future MP canvassing on behalf of one of the big parties, OK, nothing wrong with that. 
It was addressed to me by my first name only, no introduction and signed off informally with the candidates first name, the entire content was written in a way that just slated the opposite party.
Finally it asked if I would like to distribute leaflets for the said Lady or donate to her cause.
If someone is trying to sell me something I at least expect initially to be addressed by my proper name, have an introduction and yours sincerely or similar to sign off. 
Is it just me???

No I dont think it is just you. Agree if someone is "after" something and they dont know you it is polite to adress you formally imo.

I think it's a generation thing. I always insisted customers were addressed formally until they asked to be addressed by their first names. However as I became older and customers became younger, it became a bit strange for a fifty-plus year old to address a twenty-something as Mr Smith. 

In the case of women, there was also the Miss/Mrs/Ms? conundrum.

I have found that when speaking to call centres such as the AA during the annual renegotiations for membership and/or insurances, they invariably call me Mr Black until I ask them to call me Roger.

I've noticed when registering on some websites where they will be communicating by letter or email, they sometimes have a field asking how you wish to be addressed.

It’s like when complete strangers at a call centre call me ‘mate’. I can absolutely guarantee (unless your telling me I’ve won the lottery) that you are  NOT my mate .

I once did tell someone in a supermarket who called me "mate" that he wasn't my mate, that I was a customer and to remember that.  I left him with his mouth wide open in shock.

Leighton.

My father visiting the big city and using the normal devonian address of "thank you my lover" to the lady who served him got the reply "I am not your lover nor am I ever likely to be."
She was right in that sense he has better taste 

Say what you like about the French, but we always find them very polite ( when taking your money), greeting you with Bonne Jour monsieur/Madam, then Merci and when leaving Bonne Journee.

I must add that the staff in our local Lidl also are very polite, no darling or my lover etc.
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Richard