1. Singapore is very correct to pay political decision makers a high salary.

From PSD, Singapore benchmarks to top 1,000 salary earners in Singapore. Based on some simple deductions, an entry level minister earns 60% of what the 500th highest salary earner in Singapore earns and the prime minister earns 120% of what the 500th highest salary earner in Singapore, paid in a clean wage (see our minister Iswaran's corruption case for example).

The stated goals are to attract talent, to prevent corruption and to have fair remuneration for the responsibilities and work done. I think these are all well and good.

However, incidentally and perhaps more importantly, the salary sizing serves to:

a. Make up a large proportion of the office holder's income (this not only prevents corruption in the common sense where the office holder has to find other income sources to supplement their income, but it also prevents corruption in the other sense where an office holder's main income is from other sources e.g passive from already being rich or having a rich spouse (see Rishi Sunak))

b. Align the interests of the political decision makers to the employment class by making them part of the employment class (albeit at the highest end)

c. Places the job in the realm of "aspirational employment wealth" which is "attainable" by many people if they are smart and hardworking. 

d. Allows the political decision maker to hold the same amount of "power" through salary / wealth / money as the rich, who they are interacting with, i.e doesn't disadvantage them on a social standpoint and/or make them need external wealth to match the social wealth related standing. (see Jerome Powell's 200k salary while setting policy affecting billions and billionaires)

e. Doesn't overstretch the "discount" for public service ethos. (40% discount on the median of the median 1,000 salary earners because they are in the job for "public good")

f. Ideally it is stressful enough such that a very wealthy person (e.g 100+ million dollars wealth) will never choose to do it for personal gain (over public gain) while offering sufficient personal gain for the capable but not very wealthy

2. The tax code's distinction between capital and income is very abusable by the rich. It seems to me that labour derived income and capital derived income will catch the rich much better (to split income tax). On top of that, there should be certain capital / wealth taxes in itself.

a. Capital gains tax (the most prevalent form of capital derived income tax) is essentially useless if the rich can take a loan against their asset and defer the sale of the asset forever (especially if there is remission or equivalent of capital gains at death). To elaborate a bit more, this control over when to be taxed is OP and shouldn't be allowed. Presumably this was done due to liquidity but for income-derived illiquid things like stock options are also taxed upon receiving control and you have control over your capital gain.

b. Rental income / dividends income, in my opinion, should be considered capital - derived income.

c. Tricky to tax unearned capital gains or maybe a matter of political will? - if they can take loan to get liquidity without selling to avoid capital gains they could take a loan to pay taxes but of course they don't want to)

d. Corporate income tax, especially 1 tier corporate income tax is technically also capital - derived income. This is as the gains accrue to the shareholders essentially who have only contributed capital (they should be remunerated with a salary / director fee if they act in other capacity)

With this "grouping", you can then see the net rates of taxes in capital derived income vs labor derived income. If you want to cover land and entrepreneurship, you can put land pretty much into capital and entrepreneurship into labor since the remuneration would be labor derived.