Expectations about the future of policy signals matter for mobilizing big investments for these big industries. The investments in technologies to reduce emissions are long-lived. That means expected future carbon prices and expected future incentives from policy matter almost as much as current incentives.
There is a cost of uncertainty regarding the existence of policy. There are costs of uncertainty in the robustness of those systems. It's why there's a live conversation and some current policy work around an instrument called “carbon contracts for difference” to try to mobilize some of those incentives through certainty.