Cutting Corners For Real does not mean the job is / was done well.
The allpication of ceramics be it vertically or horizontally to a surface is a skilled / trade onto itself. Europeans are usually masters at this skill but in North America most residential buildings are constructed with wood framing were as in many southern European countries the predominance of homes were ceramics decorates floors and walls, homes are built with concrete, mortar, clay and blocks.
Installing ceramic tiles atop existing flooring in traditional wood framed homes can have negative consequences if a plan is not drawn out with measurements calculated..
Prior the ceramics being applied;
1: Sub Flooring / substrate; Any subfloor must be structurally sound and able to support the extra load.
Ceramic tile floors are heavy. The ceramics is a hard surfaced brittle material.
Ceramic Tiles can crack and break or even dislodge if the substrate, the surface below through deflection in the joists.. Mortar; Selecting the proper thinnest mortar for ceramic tile adds strength.
To install ceramic tiles correctly, an even flat, ridged stable surface is required.
Plywood must be installed over "an adequate subfloor" and must be at least 1 1/8" / one inch /and one eight inches thick when combined with the subfloor. Interior-grade plywood and particleboard are not considered a strong enough for a tile installation.
Cutting corners for real
In the zoomed in high definition image, you can visually determine how the ceramic installer worked.
Poor building practices. Any subflooring appears absent. If there was, the substrate did not continue to the wall.
As for the mortar, The mortar base, the thinnest, appears too thick and void of notching.
An exposed areas such as the one in this Cutting Corners For Real blog allows an individual to dissect the application and see any defective installation practices and what materials were used and how they were applied.
This old house link shows you how to apply ceramic tiles correctly.