Many tech stocks aren't splitting, despite their levels. Why?

I've been through split histories for many of the big name companies and ETFs, and I've noticed many haven't in over a decade. E.g. VTI last split 2-1 in 2008, NVidia 2007, and Microsoft in 2003. It looks to me as if they're either keeping their prices attractive for headlines or they're unsure of the market stability.