The Allies defeated the U-boats with \"mediocre\" weapons developed reactively.
Radar was developed to detect airplanes, the use of radar to detect subs was not seriously considered until the British realised (reactively) that surfaced U-boats attacking at night could not be detected visually or with ASDIC, radar provided the answer. Prior to WW2 the accepted methods for detecting U-boats were visual and audible. In fact, as you are no doubt aware, Bomber Command were loathe to release radar tech to Coastal Command.
The Leigh Light was developed reactively, an airplane equipped with radar could detect a surfaced U-boat at night but could not attack successfully due to radar\'s inaccuracy at close range. The solution -reactively- was to fit a searchlight to a Wellington.
The Liberator was the most effective A/S VLR plane in WW2, in the hands of Bulloch it was probably the most effective A/S weapon in WW2. The Lib was designed as a bomber operating over land. It did not possess the resilience of the B17 and was regarded as an easy target for night fighters. The mid-Atlantic airgap required closing, the answer lay with the Lib, it had the immense range and payload capacity to operate very effectively against U-boats far out into the Atlantic. Again the problem was solved reactively.
I could continue with hedgehog, hunter-killer groups and \"creeping attacks\" all weapons and tactics devised reactively i.e. in response to a current problem.
The Germans did not need electroboats to win the Western conflict, they could have won in 1940 by forcing the British into the sea at Dunkirk and prosecuting the airwar against the RAF, airbases and radar stations without diverting to London (going off topic?). The Germans could have won any time up to late 1942 providing they concentrated all resource in the West, primarily with U-boats and anti-shipping strikes with JU88, (incidentally, long range JU88 could have escorted U-boats across Bay of Biscay and fought off allied A/S planes, but this is another \"what if\" and, of course, is off topic).The fate of the 3rd Reich was sealed by invading the USSR (trucks or no trucks).
Your comments re: US tech are wildly off topic (and all the better for that!).
US tech did not win in Vietnam, the Gulf (Saddam is still in power) or the Balkans (only the threat of a land attack produced a result of sorts). The most effective delivery system for tactical and strategic conventional weapons used by the US is the 50 year old B52, so much for technology

Regards