Because journal entries are brute force accounting.

QB is not designed to be used with journal entries with some very rare exceptions.

the vendor transaction list shows bills entered for that vendor, no bill no transaction to list.

Journal entries should be the exception when using QB, they often do not work as you think they should, and  when you use inventory type items they never work for inventory. It is much better to use the forms on the home page the way QB is designed to be used.    Journal entries also bypass accrual/cash reporting, and will not show on many reports.