Television once produced a large number of pilot episodes each year, most of which were never seen. That system has largely been replaced by ordering full seasons directly.
The pilot was a filter for a scarce schedule
A network had a fixed number of slots and received far more proposals than it could use. Filming pilots was how it compared candidates on something more solid than a script.
Most pilots were made in the knowledge that they would not proceed. The waste was accepted as the cost of choosing well.
The economics held because the prize was large: a successful show occupied a valuable slot for years and produced a syndication asset. Against that return, discarding a dozen pilots was a rational expense.
Concentrated production made pilots expensive
Because everyone tested at the same time of year, crews, studios and actors were all in demand simultaneously. Prices rose accordingly.
Pilots were also shot as showcases rather than as normal episodes, with budgets well above what the series would later sustain.
That created a further problem: a pilot that impressed buyers was frequently unrepresentative of the show that could actually be produced week to week.
Streaming removed the slot constraint
A service is not choosing one show for one hour. It is assembling a library, and it can carry a great many programmes without them competing for a time.
The question changed from which of these is best to whether this particular thing is worth making at all.
Comparative testing is unnecessary when the decision is not comparative. The pilot's whole purpose disappeared with the scarcity that created it.
Straight-to-series buys talent as well as material
Writers and performers with options do not want to spend months on a project that may be discarded. A guaranteed order is a competitive offer.
In a crowded commissioning market, that certainty is often what secures a creator, independently of the merits of the show.
The order therefore functions partly as a hiring instrument, which is not something a pilot could ever do.
What was lost with the test episode
A pilot revealed casting problems, tonal mistakes and structural faults while they were still cheap to fix. Those discoveries now happen mid-production or after release.
Shows arrive with first episodes that are visibly still finding themselves, and audiences are asked to be patient in a way that a tested pilot did not require.
The saving is real and so is the cost; it has simply moved from the network's balance sheet to the viewer's first hour. A show that would once have been fixed in private is now fixed, if at all, in public.