First off i agree with you. To many times people think they are the only one the merchant is dealing with.( Hell i had it yesterday where a merchant told me they never applied anywhere and only working with me since their banker recommended me . I got a decline for to many credit pulls in the last 30 days with no fundings) . People need to get passed their egos .

Next is where it is past the amount of time for exclusive where the lender themselves based on the iso agreement can call it . Every lender does this and do not be naive to think other wise.This is not called backdoored. (this is why you never shot gun a deal to too many lenders at once)

Next is what an underwriter mentioned on another thread that every submission sent in cost a lender money. Now if a lender sees an iso that sent a 100 submissions and not one funded , they will get backdoored .

You also have the honest mistakes, that if you doing this long enough can happen.

Next is sneaky merchants, I had a merchant that after i sent him the docs he called the lender direct to see if he can get a better deal. This happened to be a small lender with no sales floor that told me, but any large sales floor that has sales rep will take that call get in the submission and offer cheaper.(national actually made a rule because of this that once docs requested there in house team cant get in a new submission)
Now do not get me wrong even though i understand all this, i did have lenders that straight up tried to backdoor me.