the roi is better at smaller corps that pay attention, but you would still be surprised.

and where it is more efficient its where there is better attribution models aka direct sales.

note: there are certain kinds of products that are 100% 'click driven sales'. they zero brand awareness, they want to sell you that 'fleece hoodie' on the spot. those guys have their funnel math down solid.

but startups and other companies ... not the same.

well funded startups burn $ thinking it's productive - and hugely: buying fake customers, or, spending $2 to get $1 in revenue to either pad the books, show investors, make themselves feel good or 'strategic'. FYI 'strategic' is often rational. those are big pools of money.

but usually campaigns are mixed and attribution is hard, even for smaller companies.

the tighter the budget, the more 'direct purchase', the more 'nominally efficient' it is.

also note - most ad $ is big companies who ironically spend a smaller share of their revenue on ads <- this is the power of scale.