Why does a given savings rate translate into different growth rate?
History and expectation work their way through - complementaries & increasing returns.
Some goods have network externalities
Adoption costs. no. of adopters linked with multiple equilibriums.
QWERTY is already there by the advantage of historical precedence.
Lock-in effects
When an externality is such that the cost of an action increases with the number of adopters, they cannot be responsible for multiple equilibria or historical lock-in.
Historical lock-in occurs only when externalities take the form of complementaries.

Cooperation failure
Economic underdevelopment is the outcome of a massive coordination failure.
Investments can be considered a complementary good.
Coordinated equilibria

Norms are always a hindrance and that conformity can only slow down the pace of development.
Social norms: What individuals can do is tempered by what society thinks is acceptable.
History establishes a status quo.

Coordination failure: The possibility that an economy or more generally, a group of economic agents might be caught in a bad equilibrium when there is another good equilibrium in sight.

Mavericks are important.

Status quo has an important role in determining the successes of new policies. There are gainers and losers relative to the status quo. Not important even if it raises the total pie - overall welfare.

Inverted U-hypothesis

Hirschmann Rothschild described such an increase in an individual's utility (and hence a tolerance of greater inequality) resulting from the improvement in other's economic status as tunnel effect.

The stronger the tunnel effect, the higher the tolerance.

Benefits of development seems to be very unevenly distributed among individuals. Technical progress tends to be biased against unskilled workers initially.