1) Consultant is hired to solve a problem.

2) Consultant struggles to understand the nuances of the problem.

3) Consultant relies on government employees to hand-hold them through the solution, effectively subsidizing the consultant with free labor.

4) Consultant writes it up in a final report with their company logo on the title page and gets paid.

Maybe that's not necessarily bad if it eventually solves the problem, but it does seem pretty inefficient for the taxpayer.

Consultancies have never saved the government money.

US governments hire consultants because they have been obligated to do <thing> but have not been allowed to actually hire anyone to do <thing>, which is a hilariously stupid situation but that's what happens when you are so miserable you micromanage the budget without ever thinking about downstream effects.

The government is obligated to provide it's services, and that doesn't change if the legislature didn't actually give you the OK or budget to hire anyone to do that job.

Instead, governments are forced to solve this stupid problem by paying for consultants out of more discretionary budgets. They pay well above market rates for the position too, which is insane.