ffmpeg: mp3 encoder not found

In 14.2 libmp3lame is installed. Am I correct to assume that ffmpeg was
compiled to include this mp3 encoder?

Trying to extract the audio stream for an .mp4 I created fails:
$ ffmpeg -i regulatory-science-models.mp4 -codec:a libmp3lame -qscale:a 2 reg-models.mp3             Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'regulatory-science-models.mp4':
   Metadata:
     major_brand     : mp42
     minor_version   : 0
     compatible_brands: mp42mp41isomiso2
     creation_time   : 2020-08-13T18:57:21.000000Z
     encoder         : x264
   Duration: 00:43:56.93, start: 0.000000, bitrate: 214 kb/s
     Stream #0:0(eng): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 960x542 [SAR 542:541 DAR 960:541], 109 kb/s, 30 fps, 30 tbr, 3k tbn, 60 tbc (default)
     Metadata:
       creation_time   : 2020-08-13T18:57:21.000000Z
       handler_name    : VideoHandler
     Stream #0:1(eng): Audio: mp3 (mp4a / 0x6134706D), 44100 Hz, stereo, s16p, 99 kb/s (default)
     Metadata:
       creation_time   : 2020-08-13T18:57:21.000000Z
       handler_name    : SoundHandler
Unknown encoder 'libmp3lame'

I'm trying to learn why ffmpeg cannot find the mp3 encoder.

TIA,

Rich

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