Part of the problem is that an IPO is not really a fundraising event, often, in practice. Selling shares is just a necessary part of listing. They may not be interested in funds at all.

Instead, the company wants liquidity for existing shareholders or sometimes liquid shares to use as m&a currency.

That tilts the balance in favour of paying a "brokerage fee" in exchange for de-risking and simplification. Occasionally IPOs go badly, and the potential disruption is worrying.

Like with a lot of high finance, competition is weak. So, the "price" of these services is (perhaps, idk personally) high. Also, CEOs run companies, not IPOs. Its just not really a cost you optimize and the market isn't there to optimize it by default.