Yes, but this "enterprise" crapware is the transaction system of your bank, and those "few bytes" are your last paycheck. Have some respect for the software that makes the world around you function.
They're most likely still running all their transaction processing on a single mainframe (+another one for redundancy) with something like IBM CICS [1, 2]. And they most likely also have a lot more transactions than in the 60s (card payments, internet banking, etc.).
Most banks and payment systems have old, reliable codebases, a lot of them even in COBOL. Banks don't play with those systems often, and they don't use monstrocities like J2EE for them.
It's the other kinds of enterprise systems that are crap and deserve no respect. Intranet apps in big corporations, the BS systems that always mess up your bills in services companies, slow as molasses web portals for big enterprises and organisations etc, ERP and CRM apps...