It is / should be more nuanced than that... as someone who has done fairly serious advanced training to Roadcraft (the police driving manual) - you are taught to think in a more complex way than just 'always indicate'.
e.g. road positioning is important - an example might be:
- a bus is stopped in the road to collect passengers / a skip is left in the road / some obstacle you need to go around...
- traditional driving instruction is that you indicate to move out and around the obstacle...
- however, if there happens to be a side road nearby - that indicating might be mis-read as turning into the side road and a car waiting there could choose to come out - bang - collision.
instead, by making the decision earlier and moving out towards the centre of the road, you gain a number of benefits:
- you get a better view past the obstacle
- your road positioning shows that you are aiming to go past the obstacle
- you give a better view to cars behind that a obstacle is in the road
- you don't give a false impression that you might be turning right etc. it is clear that you will continue to progress in a straight line
in that situation - no indication = better than indication.
and there are others - the main difference being that road positioning is a stronger tool than an indicator - road positioning, or where you place your car is much easier to use to predict your path as a pedestrian / other road user, than an indicator which could mean many things including that you forgot to turn it off.
On a motorway - if you move out gradually and far enough back so that the car you plan to pass could still move out in front of you, then you don't need to indicate - you are not yet in a threat position, so what you do is not affecting them - but the positioning of your car has made very clear to them that you intend to pass...
Equally, returning to the left having overtaken, why do you need to indicate? you are travelling faster than the person you have passed so what you do will not affect them - therefore you do not need to indicate...
ultimately indication is there so that you can show someone that your planned move might affect them / their decision. Ideally in driving, you drive to not affect others... so the times when you do not need to / should not indicate are perhaps more common than some expect...
back to the original point though - one of the first responses got it right - simply don't buy a new car - buy older and mend when necessary - more environmentally friendly (biggest environmental impact is manufacture / recycling of cars) - no nanny state features - etc. we drive three cars: 8 yrs old (with very little nanny state stuff) / 14 yrs old / 32 years old.