The banking limits aren't unbelievable- if you live in Japan. Its standard bureaucracy. And the 5% is likely not a withdrawal at all, but a fiat to fiat transfer through a regular bank which charges them for it (though there is obviously a percentage in it for them as well). And when a bank is forced to submit reports on incoming transfers over $10k USD (in the US) to regulatory agencies, they also aren't allowed to tell the customer they are doing so (this is a fact). So EVERYTHING is a delay EVERYWHERE.
What about SEPA withdrawals coming out from Gox's Polish bank? Why 6 weeks delay?
If reporting every transaction above $10k causes so much delay, why I can wire 50k EUR to MtGox and I get them credited in 2, 3 days max.? Why the huge delays affect only outgoing and not incoming transfers?
It doesn't add up. Other exchanges have no problems with "banking limits".
Because they don't have a lot of fiat?
Just like a bank that does not have their depositors money.
However, this is different, they don't have either the fiat or the bitcoin. So they can't open the floodgates to allow anybody to withdraw. No withdrawals at Mt.Gox. You can sell BTC and fiat to each other, but you can never withdraw!
In summary, all the BTC and fiat that's traded at Mt.Gox is mostly all fake. It is likely only 20% of the original still exists. That is why there is not enough dollars to buy the fake BTC that they are selling.
This situation could last a while before Mt.Gox gets it all squared away... or another exchange buys all Mt.Gox assets and customers. That would be quite expensive if Mt.Gox has only 20% of the depositors coins and cash.