It's not that JPMorgan doesn't make redundancies. In Q1, it let 292 people go from its investment bank.
However, JPMorgan seems less prone to big headcount cuts than its rivals. Since the end of 201, it has reduced headcount at its investment bank by 607 people and steadfastly refused to announce any bigger cuts. Goldman Sachs, meanwhile, has got rid of 3,300 people (but said yesterday that it won't be cutting any more unless things change materially).
Why is JPMorgan such a solid place to work? A graph from Nomura analyst Glenn Schorr provides a hint: while other banks' sales and trading revenues oscillate wildly (eg. Citigroup's FICC revenues were up 20% q-on-q, Goldman's were down a similar amount), JPMorgan's remain eerily steady. Therefore, it doesn't need to do any big hiring and it doesn't need to do any big firing. It's as simple as that.