Most of the associated methods are identical except for three:

readinto()
busio has these args: readinto(buffer, *, start=0, end=len(buffer), write_value=0)
bitbangio only has: readinto(buf)

write() has the same problem.
busio: write(buffer, *, start=0, end=len(buffer))
bitbangio: write(buf)

Lastly, busio has frequency() but bitbangio doesn't at all.

The learn.adafruit.com documentation does allude to busio and bitbangio being replacements but doesn't mention any SPI issues, if I remember correctly.

In my instance this means that the library for sdcard use is broken for Huzzah esp8266.

Thank you,
Stranger