A friend of mine has solved a problem that we might come across with other people. They have the Eco mode on their boiler, in other words they did not have preheating of the hot water. They were most surprised to hear my boiler come on, and upon investigation found that the Eco mode was off! They realised that this was because the electrician turned the power off when attending to a cooker switch. So what they learned was that whenever someone or something cut the power to the boiler, they will need to switch Eco mode on again when power is restored.

Why to boilers or at least that make default to not eco mode?

It probably hasn't, the main breaker was probably dumped 'cos the electrician didn't know the house and wasn't taking any chances. when power was restored every thing went into start up mode.

As to why eco. isn't the default mode - either most people don't bother or don't want to wait for the hot water more than what is in the pipes to run through so no demand to the manufactures to alter the chip they have been using for years.