Meson ignores CUDA_PATH variable on Linux

Meson ignores the CUDA_PATH variable on Linux.

phas@Hyperion ~/D/g/src> ls /opt/cuda/
bin/  doc/  EULA.txt  extras/  include@  lib@  lib64@  libnsight/  libnvvp/  NsightCompute-2019.1/  nsightee_plugins/  NsightSystems-2018.3/  nvml/  nvvm/  samples/  share/  src/  targets/  tools/  version.txt

phas@Hyperion ~/D/g/src> meson --reconfigure gst-plugins-bad -D nvenc=enabled -D nvdec=enabled
The Meson build system
Version: 0.50.1
Source dir: /home/phas/Downloads/gst-plugins-bad/src/gst-plugins-bad
Build dir: /home/phas/Downloads/gst-plugins-bad/src
Build type: native build
Project name: gst-plugins-bad
Project version: 1.16.0
Native C compiler: cc (gcc 8.3.0 "cc (GCC) 8.3.0")
Native C++ compiler: c++ (gcc 8.3.0 "c++ (GCC) 8.3.0")
Build machine cpu family: x86_64
Build machine cpu: x86_64
[...]
Dependency cuda-10.1 found: NO (tried pkgconfig and cmake)
Dependency cudart-10.1 found: NO (tried pkgconfig and cmake)
Dependency cuda-10.0 found: NO (tried pkgconfig and cmake)
Dependency cudart-10.0 found: NO (tried pkgconfig and cmake)
Dependency cuda-9.2 found: NO (tried pkgconfig and cmake)
Dependency cudart-9.2 found: NO (tried pkgconfig and cmake)
Dependency cuda-9.1 found: NO (tried pkgconfig and cmake)
Dependency cudart-9.1 found: NO (tried pkgconfig and cmake)
Dependency cuda-9.0 found: NO (tried pkgconfig and cmake)
Dependency cudart-9.0 found: NO (tried pkgconfig and cmake)
Dependency cuda-8.0 found: NO (tried pkgconfig and cmake)
Dependency cudart-8.0 found: NO (tried pkgconfig and cmake)
Dependency cuda-7.5 found: NO (tried pkgconfig and cmake)
Dependency cudart-7.5 found: NO (tried pkgconfig and cmake)
Dependency cuda-7.0 found: NO (tried pkgconfig and cmake)
Dependency cudart-7.0 found: NO (tried pkgconfig and cmake)
Dependency cuda-6.5 found: NO (tried pkgconfig and cmake)
Dependency cudart-6.5 found: NO (tried pkgconfig and cmake)

sys/meson.build:109:2: ERROR: Problem encountered: The nvdec plugin was enabled explicitly, but required CUDA dependencies were not found.

A full log can be found at /home/phas/Downloads/gst-plugins-bad/src/meson-logs/meson-log.txt