Case in point, soy gets 8% the share of agricultural government subsidies while feed for animals gets 34%: https://en.wikipedia.org/wiki/Agricultural_subsidy#United_St...
Price only reflects what consumers are willing to pay and the effects of subsidies, NOT the environmental impact...
If you ignore that, you get all kinds of obviously wrong things: a cheap gas guzzling car is cleaner than a tesla; natgas for electricity is cleaner than nuclear. etc. And worse, when you start talking about tech that hasn't scaled up yet.. if you go back 10 years, you would get: solar panels are worse than burning coal.
The price is not an indicator of environmental impact.
Obviously at the margins there are costs to environmental impact that may or may not be realized in consumer pricing and there's lots to argue about on the regulatory side.
But in general, if you have to "equivalent" products shipped and produced in bulk, and one costs 4x as much as another (roughly where "beef vs. soy protein" lands for the consumer), it's a really good bet that the cheaper one involved less energy to produce.
And to speak to your point specifically: if it were simply a matter of reducing per-unit R&D costs by achieving economies of scale, they should be selling below cost so that they can grow unit volume. It's hard to achieve economies of scale when your product is more expensive than the competition.
Its price.
When these are significantly cheaper than beef, then it'll be safe to state categorically that they are better for the environment. Until then, it's mostly a game of "pay attention to these metrics that favor my product and ignore the metrics which favor the competition".