A programme available in one country and absent in the next is normal rather than exceptional. Availability is decided market by market, and no single party has authority over all of them.
Rights are sold by territory, one at a time
A rights holder negotiates separately for each market, often through different agents and at different times. Nothing requires the outcomes to be consistent.
A global service must therefore acquire a title country by country, and any market where the negotiation failed leaves a hole in an otherwise worldwide catalogue.
Where a title was produced in-house the service usually holds all territories from the start, which is why original programming is the most consistently available.
Existing local deals block later ones
Many titles were licensed to national broadcasters years before global services existed, sometimes on long agreements that included exclusivity.
Those agreements are still in force, so the streaming rights for that market are unavailable until they expire regardless of what the rights holder would prefer.
This is the usual explanation for a title arriving in a country years after everywhere else, appearing exactly when an older contract ran out.
Music clearance breaks catalogues quietly
Music used in a programme is licensed separately from the programme itself, frequently for specific territories and media. A show can be cleared for broadcast and not for streaming.
Clearing decades of incidental music across every market is expensive, and for older series the cost can exceed what the title would earn.
The result is that some programmes are quietly unavailable everywhere, or appear with substituted music, because the rights work was never economic to complete.
Local rules shape what can be offered
Several markets impose content quotas, classification requirements or investment obligations, and meeting them changes what a service chooses to carry.
Classification alone can be enough to delay a title, since some territories require formal certification before anything is made available.
These requirements vary widely and change over time, so a catalogue that matches in two markets this year may not next year.
Why the gap is rarely explained
Services do not disclose which titles they failed to acquire, because doing so reveals negotiating positions and highlights weaknesses in a local catalogue.
From the viewer's side this looks like an arbitrary refusal, when it is usually the visible edge of a deal that was never signed.
The practical consequence is that catalogue comparisons between countries measure licensing history rather than any deliberate decision about what a market deserves.