That might be the case if they were showing it in a slot normally used for regional programming, but it's actually being shown as an opt-out from Paul O'Grady's Animal Orphans, and is followed by a repeat of Sean's Scotland.
Paul O'Grady: for the Love of Dogs has been shown in that slot for the last few weeks, which STV haven't opted out of.
Animal Orphans is a repeat whereas Love of Dogs wasn't so that could be a reason.
The High Road tribute is getting a pasting elsewhere - comments about it scraping the barrel and STV being out of touch with their audience.
Personally, I don't see anything wrong with it. Its no different to the old episodes of EastEnders, Corrie, River City etc that have been aired recently and it looks like location filming has been done for it (photo of Emma Cameron in Luss on the digiguide page) so it's not all just old footage.
Why have they opted out of a relatively popular programme and not played the documentary in the slot that Scotland tonight is usually in. This is just my opinion but I think people would rather watch a programme about dogs since we’re a nation of dog lovers than a documentary about a show many of the younger generation won’t have even heard of Including myself and then a repeat of Sean’s Scotland.
GMc's post above possibly alludes to why. As does the fact that Animal Orphans is a repeat (first shown in 2014).
Also, looking ahead to Wed 19th, it appears the programme is as dispensable to ITV as it is STV, being dropped for the new series of Heathrow: Britain's Busiest Airport, so there was no point in STV tagging along when the schedule could be better used.
With limited opt-out opportunities and STV needing to minimise the amount of backlash from viewers (because there ALWAYS will be some), what is to happen is perhaps the best solution.
Regarding the opt-out window on Thursdays where Scotland Tonight and Tonight usually go head-to-head, you raise a good point about the timing of opt-outs. Currently, ITV are showing Eat Shop Save here. STV haven't aired the first two eps of this because Tonight took its summer break a fortnight earlier. In an ideal world - and irrespective of which day they showed the High Road tribute - STV would be skipping Eat Shop Save entirely to avoid confusion for viewers but, hey-ho, they aren't and are dipping in halfway through the series.
High Road and Sean's Scotland aren't exactly earth-shattering I agree but what is the alternative?
It was announced this week that STV's output for non-current affairs programming in 2019 decreased by 90% (!) to 40 hours compared to 403 hours in 2018. https://www.ofcom.org.uk/__data/assets/pdf_file/0009/200502/media-nations-2020-scotland-report.pdf
BBC Scotland has swallowed up the market.