HONGKONG provides more proof than most places that there is truth in the saying that money is the root of all evil. Yesterday's demonstration outside Government House over the Housing Authority's double-rent policy hardly rates as a crime against humanity, but the attitudes displayed by the protesters have nothing to recommend them. Self-interest prevailed as public housing tenants blocked a busy road for hours in pursuit of their claim. To those living in squatter huts or temporary housing areas, and waiting for the allocation of a flat in a public housing estate - especially new immigrants from China who have to wait years to qualify - abolition of the double-rent policy would be a slap in the face. There are now 62,500 households paying double rent. For every wealthy tenant being subsidised by the taxpayer to remain in public housing, someone on a third of his income or less is being deprived of a flat. Abolition would merely increase the subsidy to the better off. It would also cost the Government $400 million a year in lost rental income, thus diluting the present system by which wealthier tenants are effectively cross-subsidising single-rent payers. What will be even more galling to the average unsubsidised householder is the fact that yesterday's Housing Authority decision at which the demonstrators were so outraged will actually reduce the number of tenants expected to pay double rent. By introducing a new category of one-and-a-half-rent households for those at the lower end of the scale, and excluding the elderly from the policy, the Authority has made life easier for thousands. To pay double rent, the family must now earn three times the income limit for new public housing tenants. The Authority offered another concession by allowing a further 3,000 existing double-rent tenants to apply for overcrowding-relief transfers to larger accommodation. In addition, the income thresholds beyond which the increased rents come into force have been increased by 13 per cent over the previous year - more than the rate of inflation. Tenants on some estates will claim they are worse off because of rent rises of up to 22 per cent which were agreed last November, but a family of four with a total monthly income of more than $19,000 who pay a maximum monthly rent of only $1,600 has just been granted a reprieve. It will now be paying a single rent of $800 per month. If its joint income rises to $22,800 per month, it will be paying an extra $400 in rent. Only if its income rises to $34,200 per month will the full double rent policy come into effect. By that time, if the income is earned solely by the tenant and his wife, the family will be in the 15 per cent flat-rate tax bracket. It was the opposite argument which persuaded legislators last December to vote 26-22 in favour of scrapping the double rent policy. The United Democrats carried the debate that public housing was a form of social welfare rather than a commercial commodity, and rent policy should not penalise those who have pulled themselves out of poverty by hard work by defining them as rich tenants and forcing them to pay double. Mr Lee Wing-tat, one of a very small minority of grass-roots representatives on the HousingAuthority, argued with some force that a society that expected a teacher and a billionaire to pay the same 15 per cent rate of tax should not be asking better-off tenants to pay more. Not even Social Services representative Mr Hui Yin-fat could shake the Legislative Council's view. The Association for Democracy and People's Livelihood member Mr Frederick Fung Kin-kee, who sits on the Housing Authority, and other grass-roots representatives continue to claim this is an argument of principle; they can offer no other defence, since itwould be difficult to justify a case of widespread hardship on the basis of the rent increases involved. There is no doubt that the Housing Authority underestimated the opposition to its plan, fuelling accusations that the outgoing chairman, Sir David Akers-Jones, and his colleagues are out of touch with their public, but misreading popular reaction does not invalidate the figures, which remain convincing. The one-and-a-half-rent policy is the Housing Authority's attempt at a compromise, but there should be no more back-sliding. There can surely be no sympathy for people who are well able to afford to pay more than the ridiculously low rents currently charged, especially when that selfish resistance is at the expense of people who genuinely need cheap housing.