why did unemployment in the 1980s not have this effect?
In the 1945 election, Labour called for the outright nationalisation of 20% of British industry, coal, steel, gas, utilities and all transport, with highly centralised planning of the remaining 80% of industry. Government's idea was to organise production more efficiently, insulated from the vagaries of the market, with a guarantee of high wages and full employment. The successive Conservative governments did little to change all this, seeming to swing to the left, much as Cameron seems to be doing now and the result was a slow slide into the sick man of Europe and a plea for the IMF to bail us out in 1976.
Margaret Thatcher seemed to be unusual in that she understood how markets really worked. She believed that jobs, in a free society, depended on competition, earning a profit, satisfying customers and NOT on government. Unemployment in the 80s was a result of that painful adjustment back to those fundamental principles of business and a breaking of the destructive power of unions.
Unemployment now is due to nothing short of the opposite, of a willful destruction of competition, the profit motive, customer satisfaction and, therefore, a reliance on government. The end result can only be economic collapse, sooner or later unless we learn the lessons of May 1979 all over again.