Unfortunately you can't assume this anymore. In fact its been a problem for 6+ years easy.
LEDs used to last almost forever, or so it seemed. This was until they learned how to make them dirt cheap, then failures started showing up.
Only comparison I can offer is in the 1980s-1990s a T1 style LED was $3-5 each. Today they can be had for pennies when purchased in quantity. On top of that, the higher the output the shorter the life. Obviously on a brake light or reverse light the use is intermittent, but with the quality we see often I'd still expect failures.
Yes, as things progress and production goes up prices often drop, but in this case so has the quality.