I will admit it is common courtesy to contact a potential customer, even by text, just to say I am not interested, too busy, etc.
But also applies to potential customers to contact me to say they have decided to accept another quote etc.
Reasons why I do not quote or contact some people are, -
Time passes because I am busy and I sometimes get embarrassed to contact the person,
or
I get a lot of work elsewhere before quoting,
or
I discover they are getting other quotes,
or
I think the person is dodgy,
or
They are attempting DIY work, or involving cowboy trades,
or
Job site/property is filthy,
or
Existing plumbing to remain is shoddy or dangerous.
I find it strange that many people outside the building trade will choose the best job they can get for themselves, often leaving good jobs just to take a slighter better job, (easier or better paid perhaps).
Yet they wonder why plumbers and other trades do the same! 😵
Got to remind people that we might not actually need their job or their money.