No one said it was being ignored, but like with most government things, they throw money at it, and don't really fix it.
The oversight on waste-fruad-abuse runs from zealot level for some stuff, to a complete grifter state on other things. USAID was a grifter state. Ukraine is a Grifter State - that's why #blueanon fiercely opposes auditing.
USAID also not being disbanded, so there is no constitutional crisis (I mean

). It is absolutely 1000% within the purview of the Chief Executive to realign any Federal agency that falls under the Executive Branch.
Bush, Barry and President Full Lid made multiple alignment and structural changes to USAID, unfortunately that only served to expand the USAID Grifter State.