Capital is absolutely not unconstrained! It is one of the most difficult things for a bank to increase its capital base.
Base money is a low percentage compared to bank money - its true - but all bank money is a claim on base money. Pull out the base money and every bank has a liquidity crisis and would in turn have to recall every loan. More than parking meters would feel it; a bank cannot issue a loan without appropriate capital base, and only high quality liquid unencumbered assets can be considered capital, which cannot be created by a bank (a new loan/deposit is not an unencumbered asset). In practice capital can only be increase by a new share issue or by retaining profits over years.
Base money is a low percentage compared to bank money - its true - but all bank money is a claim on base money. Pull out the base money and every bank has a liquidity crisis and would in turn have to recall every loan. More than parking meters would feel it; a bank cannot issue a loan without appropriate capital base, and only high quality liquid unencumbered assets can be considered capital, which cannot be created by a bank (a new loan/deposit is not an unencumbered asset). In practice capital can only be increase by a new share issue or by retaining profits over years.