Falls from height have been the leading cause of workplace fatalities in Great Britain in almost every year since 2001. In the 2024/25 reporting period, 35 workers died as a result of such falls, over a quarter of all worker deaths that year. The construction sector bears a disproportionate share, and within construction, pitched roof maintenance is among the highest-risk activities. This paper introduces the Access-Cost Trap, a structural dynamic in the residential roof cleaning market where the dominant cost of safe access (scaffolding) and the dominant cost of fall prevention are the same line item, creating a market-level incentive for safety underinvestment that enforcement alone cannot resolve. Three testable propositions are derived and evaluated against HSE prosecution data, industry pricing evidence, and the academic literature on automation and occupational safety. The paper situates this problem within established occupational safety theory, Heinrich's accident triangle, Reason's Swiss Cheese model, and the hierarchy of controls, and extends it to argue that autonomous drone-robot systems represent a qualitatively different intervention class: they address the trap at its root by eliminating the need for human height exposure entirely, rather than adding further management layers above it. Drawing on peer-reviewed evidence from comparable autonomous systems (Kishor et al., Scientific Reports, 2025; De Simone et al., 2025, working paper) and the Law Commission's May 2026 final report on aviation autonomy, the paper concludes with the Autonomous Roof Maintenance Adoption Framework (ARMAF), a three-pillar policy roadmap with specific recommendations directed at the HSE, the CAA, and the NFRC.