All the problems observed with conventional public clouds have not been solved either by Free and Open Source Software (FOSS) alone.
Most solutions (Kubernetes, OpenNebula, OpenStack, OpenSVC, Proxmox, XCP-NG) have their strengths but are overall insufficient to build a complete cloud per se. Many features are missing. Much integration effort or custom development is required to cover those missing features.
If one needs a proof of this situation, simply observe OVHCloud, the largest cloud operator in Europe and one of the top-10 cloud operators in the world. Despite the fact that OVHCloud operates already both OpenStack and Kubernetes clusters, the company ended up purchasing a license of Anthos software from Google to cover the feature that were missing.
What is needed to build a cloud in addition to virtualisation software such as qemu/kvm or orchestration abstractions such as containers or nano-containers, is what people call an OSS/BSS software in the telecom industry. The term OSS/BSS stands for operation support system and business support system. It is a kind of cloud ERP which encapsulates operation management, orchestration, disaster recovery, monitoring, lifecycle management, issue tracking, accounting and billing.
Rapid.Space is built around one of the only open source cloud software which supports all the OSS/BSS requirements for a cloud. It provides a service profile format to specify what is a "cloud service" by encapsulating self-healing, monitoring, accounting, disaster recovery, portability, system upgrade, resource sharing and delegation in addition to basic build and run.
In addition to OSS/BSS, a complete cloud service requires tight integration with the network operating system (NOS) down from the top-of-rack (ToR) switch up to the global end-points of the CDN. This also something which is rarely covered by most FLOSS solutions besides SlapOS and Rapid.Space.
Yer, even though SlapOS covers all those OSS/BSS features, it is still not enough. Without formalised operation management procedures to train and organise staff, it takes about two years to acquire the know how and operate a cloud.