Unisons between a cross-staff voice and a normal voice are presented differently

1) Write two voices on the upper staff, reaching an unison, one being a half note and the other a quarter note. Both noteheads appear separated.
2) Now write two voices on different staves reaching an unison, but make one of the voices cross-staff. Then the heads are overlapped, so the half note head is completely covered by the quarter note head and no hint is found as to its real duration.