This point is not often recognised: it takes just as long to teach a child (or indeed an adult on a vocational training course, for example) today as it did 20 or 200 years ago. The same is true of caring for the young or the elderly, or providing a meal in a restaurant. Technology does not in itself make these activities more productive, because in these occupations quality is a more critical issue than quantity, and people haven't become inherently better learners since the 19th century. (This relates to the points I made in my earlier post on craft, about mass production techniques being inappropriate in education.) But the point needs stressing because in many other areas of work and production, salaries rise in response to productivity gains. 'Teachers' salaries however, like those of other 'efficiency-resistant' professions, rise in response not to productivity gains in education (which have thus far proven extremely difficult to achieve)' - or indeed to measure accurately - 'but to higher salaries in other sectors. This means that staff wages consume an ever larger share of the budget, even if education does not improve. And because the reasons for this are not immediately apparent to the average voter, dissatisfaction with education budgets may also grow.' There also seems to be an implicit assumption among politicians that introducing new technology inevitably results in increased productivity. A great deal of research says that this is not the case in any clear and straightforward way - and see, for example this post from 'Creative Catalyst': Technology Does Not Make a Classroom Succesful, the Teacher Does.
This rather grim point was made 15 years ago by Paul Pierson, in 'The New Politics of the Welfare State', World Politics, 48.2 (1996): 143-179.