People seem to forget that you can "price the round" without selling priced shares and incurring all the associated headache/expense if you just treat your convertible note like the warrant that it is and have it convert at a predetermined price. I've done it several times myself.
When you do a priced round, you have to go in and change many aspects of a company's legal structure. For example, the documents drafted in a priced round may include amendments to the charter, a voting agreement, a stock purchase agreement, a right of first refusal agreement, a shareholder agreement. Drafting the legal docs for a convertible note or SAFE is less intensive and time consuming.
Amendments, right of refusal, etc do not happen in SAFE rounds. Why do we assume they should happen in a priced round? Seems like all these documents have been generally standardized so the cost should be the same barring investors asking for extra rights in a Series A.
A couple other things: the level of due diligence is typically higher in a priced round, which eats up lawyer time. Also it's customary (for reasons no one can clearly articulate) that the investor(s) legal fees are paid by the startup in addition to its own.