You’re basically correct. Over 150k-300k miles (it depends), it’s not uncommon for a reliable ICE car to need an engine rebuild from a blown head gasket or sometimes replacement with an engine from a junkyard pull or rebuild. Ditto the transmission. I am unsure what the probability for this is, but all mechanical systems wear out eventually.
An EV uses lithium ion batteries that typically are listed as lasting around 1.5k-2k cycles when cycled to 50% and charged gently. (supercharging, deep discharges, charging them fully all reduce the life). Taking 1500 * half capacity, an EV with a 230 mile pack could be expected to go for 172k before needing a battery replacement, junkyard pull, or rebuild. The LR Tesla with 50% more range also has about 50% more life, or 258k.
There is a Tesla that has 300k miles on the odometer, but it is not on it’s original battery.
So yeah, I basically agree with you. An EV’s core system - the battery - isn’t really going to last any longer than reliable ICE engine systems. You don’t need to do oil changes with an EV, but that’s not very much, especially with the new 15k mile synthetics, where a vehicle might need 10-15 $75 oil changes throughout it’s entire lifespan.
The other weak point on an EV is the high power motor and inverter electronics. At least with solar panels, these are the weak point - it’s not uncommon for them to fail every 10 years. The actual failure rate is probably highly variable, but this is a significant failure-prone component that ICE cars don’t have.
Basically, you’re replacing the engine, belts, and transmission (all failure prone items on an ICE vehicle) with a battery and critical drive electronics that serve as the equivalent to a transmission. I suspect in the long run, with well engineered EVs, they will fail about as often as well engineered ICE cars.
The one bright spot is that you could build an EV to be modular in a way that ICE cars are not. You could in theory make the battery a set of plug in “modules” that can be separately unbolted and lowered from underneath. They could be changed by anyone with a jack and an impact wrench. The EV’s computer would tell the mechanic exactly which module is suspect. Similarly, the inverters could be made as separate modules that are easily accessible, with easily accessed shutoff valves so you don’t spill coolant everywhere when changing one.
Alas, this is not how Teslas currently do it. The battery is a 2000 lb, single piece subunit, there is a real danger of electrocution if shade tree mechanics work on it, and the inverters are a pain in the ass to swap.