hmmm… that is not exactly correct… and to be fair, when terrain is open and you must cross it (as it was at the time), there is no option but to move across the open terrain. Germans also did the same in Poland except that they had more fire support. During Bzura counter attack, the Poles knew what they were facing but had no choice but to push on.
Bzura counter attack in the initial stages was quiet successful and forced the German commanders to respond to it quiet quickly and with additional forces. Having said all that, other allied forces did not fare much better with their tactics (then the smaller and more poorly equipped Polish forces) later when faced with the invading Germans despite all that was already demonstrated in the 1939 invasion of Poland and despite having more time to prepare (for German attack) and having better armed forces.

Among tanks eliminated by Orlik from his small tankette on the 18th of September there was German PzKpfw IV Ausf. B tank of Leutnant (or Oberleutnant ?) Victor IV Albrecht von Ratibor – commander of a platoon. The whole of his tank platoon was eliminated during that combat and Prinz Victor IV Albrecht von Ratibor was heavily WIA and severely burned – and after a few minutes he died.
On 19th of September Orlik eliminated 7 German tanks (from Panzer-Abteilung 65 or from I battalion of Panzer-Regiment 11) during the battle of Sieraków. Most of those 7 tanks eliminated (most probably 6 of them) were Pz-35(t) tanks.

Plutonowy Orlik's tankette was one of 2 tankettes from 71 armoured dyon of Wielkopolska Cavalry Brigade (both of them were TKS tankettes with 20mm guns) which broke through to Warsaw (during the night from 20th to 21st of September 1939). He was later fighting in Warsaw until 28th of September 1939.

As can be seen in the example above, this type of the Polish tankette (with 20 mm gun) was quiet useful at 1939 standard – this usefulness was experienced by a number of German tank crews to their own detriment as illustrated above.

Twice, no less!