Ordering inspections such as this is common airworthiness practice - only noteworthy here because of the number of aircraft involved. It's a bit misleading to

Ordering inspections such as this is common airworthiness practice - only noteworthy here because of the number of aircraft involved. It's a bit misleading to say they've been grounded; typically what you'd issue is a special/out-of-sequence inspection to be carried out before next flight, which I suppose to someone outside the industry amounts to the same thing but there's semantic difference. These aircraft are being inspected to ensure they are airworthy and conform to the approved type design; they're not really being "grounded" which would imply they're not airworthy or not compliant with the type design (which is the case for e.g. the MAX 8).