Have you considered Foreign exchange risks? What about
flexibility in repayment when using the domestic banking structure
for domestic transaction purposes? And just because your aware of
these existing rates doesn't mean that those are the only rates
that the banks are offerring. In fact, banks do offer their premium
or high net worth clients a better rate then the rest of the
public. Thats capitalism for you. 
On a side note, are you guys aware why the banks are actively
selling their unit trusts? Its just a clever way to transfer their
risks to the consumers as there are associated risks and costs
involved in holding too much raw cash. What about the risks and
returns of those supposedly "higher-yielding unit trusts"? Read the
fine print carefully to find out the disclaimers they put into the
contracts in order to cover their assess and bottom lines.
Generally, foreign banks [like SCB and Maybank] are prepared to
offer higher rates attract more SGD deposits. Because they will
usually go into inter-bank markets to borrow from local banks like
DBS, which has the largest depositor base.
When banks sell units trusts? They largely earn fee incomes for
selling the units trusts and managing the funds. For some banks,
they don't even manage these unit trusts, but simply play the
channel distributor for fee incomes. For example, they sell life
insurance coverage for underwriters like Prudential and AIG. Thus,
they don't 'transfer risks to the consumers'.
What is deemed 'high net worth' have been re-defined quite
often. These days, private bankers defined people with surplus cash
of $1m in bank account as too small to be their customers. Some
banks also are reluctant to offer higher deposit rates for $1m or
less.
