Agnes.
You say Mrs Bennet didn't know what Jane's feelings were. Maybe not directly spoken by Jane, but she would surely have either drawn the situation in or sent Bingley scurrying for the hills. To save lots of quoting space, obviously we have different views. Mine hang heavily on Pride and Prejudice being a very clever story that isn't first and foremost about love, but about characters, feelings and events. Jane and Bingley, whilst important parts of the tale, are props around Lizzie Bennet. Even Darcy takes second place to her in much of the events. If the Jane and Bingley scenario hadn't had its complications, where would the sisters have fitted in, and the Gardiners used as convenient location props to move it all around. Mr Collins is another clever piece of link-up by J.A by being made a distant cousin and heir apparent to Longbourne thus using Lady Catherine Darcy's aunt and Collins's mentor as yet another way to link locations up and make a convenient meeting place for Lizzie and Darcy. Charlotte Lucas is another example of cleverness, because without her marrying Collins, why would Lizzie ever visit Kent or meet Lady C? In the same vein, taking Bingley away from the action is purely a suspension, as is moving Wickham off the board for a while. How to get it all back together? use an event that has a sting in the tale to throw them all into each other paths. Very clever plotting and one of the main reasons I admire P&P so much. Jane and Bingley are convenient padding rather than central to the story as purely major players. "Made for each other" might well be a very relevant statement.
You asked why double standards? In the friendly argument Darcy wanted to itemise everything methodically about Bingley making a quick decision and upping stakes without a major debate.. In Bingley's case he almost kidnapped him into instant action without much time to even think.
These are of course my views and not claiming to be otherwise.