LEDs would be more expensive to replace.
Not once they become the norm. LEDs are cheap to make, their premium price right now is mainly related to them being a custom part. Most places like walmart sell them for the similar price (10.98-12.98/pr). And from Amazon they are within pennies of each other.
So while they are 'more expensive' it's essentially a rounding error difference for each, and they should last much longer, meaning by the time you do replace them you may have already had to buy 1 or 2 pairs of those lower visibility incandescent bulbs, moving the savings in favour of the LEDs.
I am colorblind and do NOT care for amber rear turn signals. They look like brake lights are on...all the time.
How does colour have anything to do with them being on/off? In what scenario are amber turn signals on 'all the time'?
The argument is fallacious, your issue is with blink pattern or with on/off settings, and if you know the difference between the Export and the N.American pattern, you'd know that the N.Am. pattern actually shares the brake lights while the Export models add a specific separate light, which is why the wiring isn't the same and you can't swap Euro for N.Am.
So what you're complaining about would be solved by having a distinct turn light.
This hesitation would seem to be a benefit if it makes people pause a bit to become more aware of the situation.
Hesitation or unnecessary stopping isn't a good thing, especially on highways and rural roads where there is less road illumination detail, and often the only indication of driver intent is those rear lights not the ability to see where the road splits or there's an intersection.
Indecision and confusion in general are bad things. Making it perfectly clear the intention of the driver is best for everyone, so providing more information rather than less is a good thing.
However, most importantly, NHTSA shows that amber rear turn signals improve safety, especially on crashes of such a speed/severity that they result in injuries.
Both NHTSA and the IIHS recommend all mfrs switch to Amber rear turn signals with NHTSA submitting the requirement in their latest regulation update to conform with the NCAP norm because they know from testing that it's a better system than sharing not only the same colour, but the same bulb as the brake light.