IIRC there were a lot more options by the time of the Truecrypt-Veracrypt shift. Truecrypt was around when drive encryption was otherwise an expensive enterprise software thing, but I think Bitlocker was included with Pro versions of Windows by the time of Veracrypt so that probably became the easiest free option - and probably with better compatibility as well.
Being able to sniff a key as it transits a local bus is a very different kind of compromise of "trust" than believing that something is preemptively backdoored by a threat actor. It is deeply mysterious that Microsoft don't simply use TPM encrypted sessions to prevent this, though.
No? Any modern disk encryption system with a strong passphrase (basically, anything but default-BitLocker) is very effective against "they have your physical machine and it's off" for any known, current adversary. And, the basic cryptography in use is common, robust, and proven enough that this is probably true even if your tinfoil hat is balled quite tightly.
Where modern research effort goes is into protecting against "they HAD your physical machine and they gave it back to you" or "they got your machine while it was on/running" - these are much more difficult problems to solve, and are where TEE, TPM, Secure Boot, memory encryption, DMA hardening, etc. come into play.
this presumes that anyone would trust bitlocker.
https://pulsesecurity.co.nz/articles/TPM-sniffing